From the moment he launched his campaign, Trump has made hardline opposition to immigration his signature campaign issue. He's attempted, with varying degrees of success, to separate immigrant families at the border; ban citizens of certain Muslim-majority countries from entering the United States; rescind DACA; circumvent restrictions on detaining immigrant children; limit asylum applications from migrants; reduce the amount of legal immigration to the country; and much more. By any measure, Trump has pursued a far-right, nativist agenda on immigration.

Sanders' view on immigration is complicated, but by and large, he's relatively progressive on the issue. The Vermont senator said on CNN's State of the Union that he supports DACA. He said at the 2016 Democratic primary debate in New Hampshire that he also supports a path to citizenship for undocumented immigrants in the United States, and in a letter to President Obama in 2014, said he supports asylum for families fleeing violence in Central America. Sanders voted against defunding sanctuary cities in 2018, and told CNN that splitting up families at the border is "heartless."

However, some of Sanders' views on immigration have been criticized by progressives and applauded by conservatives. He said in a 2007 press release that low-skilled immigration to the United States drives down American wages, and opposed the 2007 immigration reform bill, though he said at a 2016 primary debate that this was because the guest worker program it included would have amounted to what he described as "modern slavery." Sanders wrote on Twitter that he wants a "restructuring" ICE, the creation of which he voted against in 2002.

At a November 2017 press conference, Harris expressed support for DACA, and said that she wouldn't vote for any government funding bill that didn't protect the 700,000 "Dreamers" — undocumented immigrants protected by DACA — from deportation. She's said on Twitter that she supports a path to citizenship, and introduced a bill in the Senate to ensure that detained immigrants have access to legal counsel.

However, Harris has been criticized for supporting a 2008 policy as district attorney of San Francisco that had the city deporting undocumented youths who had been arrested, as PolitiFact reported. She told MSNBC in 2018 that "ICE should exist."

Warren voted against defunding sanctuary cities and has denounced the Trump administration for splitting up immigrant families at the border. She said on the Senate floor that she supports the DREAM Act, and at a 2018 rally in Boston, she called for "replacing ICE with something that reflects our morality and that works," according to the Hill. Warren also co-sponsored legislation in 2016, the Fair Day in Court for Kids Act, to guarantee legal representation to undocumented children facing deportation.

Booker introduced legislation in 2017 that would ban state and local law enforcement from arresting people under suspicion of having violated federal immigration laws; effectively, this would make every city in the United States a sanctuary city. Booker wrote on Twitter that the U.S. government has a "moral obligation" to pass the DREAM Act, and told NJ.com that the United States should welcome Syrian refugees.

Booker brought a Dreamer as his guest to Trump's second State of the Union address, and in a 2018 appearance on MSNBC, he criticized Barack Obama for detaining immigrant families during his presidency. Booker also co-sponsored the Fair Day in Court for Kids Act, and called for "taking a serious look" at ICE in a 2018 interview with HuffPost.

Gabbard voted for a bill to ban DHS from separating immigrant families at the border and co-sponsored the DREAM Act.

In 2015, however, she was one of few Democrats to vote for a bill to impose additional restrictions on Syrian refugees entering the United States. The year before, she put out a press release calling on Obama to suspend the Visa Waiver Program for countries with "large numbers of Islamic extremists actively fighting alongside" ISIS and other terrorist groups in the Middle East.

As a congresswoman from a conservative district in New York, Gillibrand voted to increase funding for ICE, and said in her 2006 campaign that securing U.S. borders is a "national security priority," according to CNN.

Now, Gillibrand has called for abolishing ICE on Twitter and, according to her campaign website, supports expanding DACA and accepting Syrian refugees. She's expressed regret for her past positions on immigration, telling CNN's Jake Tapper that they "certainly weren't empathetic, and they were not kind, and [she] did not think about suffering in other people's lives."

As the governor of a non-border state who's never served in the federal government, Hickenlooper has a much smaller record on immigration to draw from than some of the senators on this list. That said, he did sign an executive order in 2018 that banned state resources from being used to enforce the Trump administration's policy of separating immigrant families, which the order referred to as "cruel and un-American." He also said that it would be "crazy" to try and deport all undocumented immigrants, according to the Associated Press.

Castro, formerly the mayor of San Antonio and Department of Housing and Urban Development chief under Barack Obama, has denounced Trump administration's immigration policies on Twitter and elsewhere. He's also told CNN that he opposes the Trump administration's restrictions on asylum eligibility for Central American refugees. Castro said in a 2013 congressional testimony that any immigration reform passed by Congress should include a path to citizenship for undocumented immigrants.

The Washington governor opposes several of the Trump administration's flagship immigration policies. He denounced the travel ban at a 2017 press conference, called family separation "an intentional infliction [of] abusive behavior to punish innocent children" at a 2018 press conference, and called Trump's unsuccessful attempt to repeal DACA "cruel" in 2017 a press release. As a congressman, he voted against bills to construct a border "fence" and mandate the reporting of hospitalized undocumented immigrants to federal authorities, while supporting a measure to allow some non-citizens to remain in the country as they pursue residency. As governor, Inslee increased state funding for a nonprofit that provides legal services to undocumented immigrants, as the Spokesman Review reported.

The mayor of South Bend, Indiana, supports DACA and a path to citizenship for undocumented immigrants, as he explained in a 2017 interview with WSBT, and he told CBS News that Trump's deployment of U.S. troops to the Mexican border was "a waste of time." Intriguingly, he suggested in a 2017 HuffPost op-ed that the Trump administration's crackdown on undocumented immigrants is actually a betrayal of traditional conservative values.

O'Rourke has made it abundantly clear that he opposes a U.S.-Mexico border wall. Calling it a "symbol of division," he's released several videos outlining why he believes that a wall would be a bad idea, the Hill reported. He told MSNBC in February that he wants to take down part of an existing border fence in El Paso, and introduced legislation in 2017 that would protect DACA recipients from deportation. He wrote a Medium post in 2017 expressing his support for the DREAM Act.

At a 2006 Senate debate, Klobuchar proposed building a fence on the U.S.-Mexico border, and said that the federal government should "stop giving amnesty to companies that are hiring illegal immigrants." At that same debate, she endorsed a path to citizenship for certain undocumented immigrants, and reiterated that position in a 2018 interview with ABC News. Klobuchar also told ABC News that the Trump administration's family separation policy is "horrendous," but when asked about the prospect of abolishing ICE, said that "we are always going to need immigration enforcement."

Williamson has expressed strong support for immigrants on her website. She supports DACA, the DREAM Act, a path to citizenship for all immigrants in the United States, and protections for LGBTQ immigrants, according to her website. Williamson also wants to speed up the asylum approval process and reduce the number of immigrants in ICE detention, although she hasn't specifically called for the elimination of ICE, according to her website.

Yang has more conservative views on immigration than most, perhaps all, of his Democratic opponents. He writes on his website that the 11 million undocumented immigrants currently in the United States are "not supposed to be here." Any pathway to citizenship "must reflect the fact that these individuals tried to circumvent our legal immigration system," Yang says on his website, and should only be considered "after securing our southern border."

He supports the DREAM Act "as a part of comprehensive immigration and border security reforms," he says on his website.

Delaney, who launched his presidential campaign way back in July 2017, supports a path to citizenship for undocumented immigrants and allowing more refugees to resettle in the United States, as he says on his campaign website. On his old 2012 House campaign website, he said that immigrants should first be required to register with the government, pay back taxes, and learn English before being granted citizenship. He also stated there that the government should crack down on employers that "knowingly hire undocumented immigrants."

In a 2018 op-ed, Messam denounced a bill making its way through the state legislature that would prohibit sanctuary cities in the state and require state and local officials to enforce federal immigration laws. The year before, he proposed making Miramar a "safe zone" for undocumented immigrants by requiring immigration officials to procure warrants before entering city-owned buildings and some schools, 10 News reports.

In 2006, Ryan voted for a bill to construct a fence along the U.S.-Mexico border. Aside from that, he's generally adopted liberal positions on immigration. In a 2017 press release, Ryan condemned Trump's attempt to repeal DACA as "heartless," and he voted for a version of the DREAM Act in 2010. In 2004, Ryan opposed a bill that would incentivize hospitals to report undocumented immigrants in their care to federal authorities.

At a 2007 Democratic primary debate, Gravel said that he's "ashamed as an American to be building a fence on our southern border," and accused immigration hawks of "scapegoating the Latinos" for America's own economic problems, as the New York Times reported. At that same debate, when asked if he supports sanctuary cities, Gravel replied that "this whole nation should be a sanctuary."

According to OnTheIssues.org, Gravel said at a different 2007 Democratic primary debate that federal immigration raids that separate families are "abominable," and that as a first-generation American, he "honor[s] anybody that comes to this country as an immigrant."

On Twitter, Swalwell has stated his support for DACA and the DREAM Act, as well as his opposition to family separation. He also co-sponsored a bill in 2016 to guarantee that child immigrants facing deportation be granted legal representation and access to evidence during court proceedings.

According to PBS, Moulton supports a path to citizenship for DACA recipients. He's also voiced support for securing the border and streamlining the immigration process to benefit small businesses.

Weld, who's challenging Trump for the Republican presidential nomination, has likened Trump's immigration proposals to those of Adolf Hitler in Nazi Germany. According to PBS, he also supports more H1B1 work visas for immigrants.

Biden has voted for several pieces of immigrant-friendly legislation, including the Immigration Reform and Control Act, which granted amnesty to 3 million undocumented immigrants, and the Violence Against Women Act, which allowed undocumented women in abusive marriages to apply for legal status without approval from their husbands. He also voted against 1996 bill that would have imposed strict limits on family immigration to the United States. More recently, Biden called Trump's efforts to repeal it "cruel" and "inhumane."

However, Biden has voted twice to build more fencing on the U.S.-Mexico border, and supported a bill to ban immigrants with HIV from entering the United States. He also voted to increase border patrol, increase penalties for immigrants who use fraudulent documentation, and impose various other restrictions on immigration via the Immigration in the National Interest Act.

Bennet is a co-sponsor of the DREAM Act. However, in 2018, he and several other senators proposed ending the Diversity Visa Program, blocking Dreamers from sponsoring their parents and giving Trump $1.6 billion for a border wall, plus an additional $1.1 billion for other border security measures, in exchange for granting a path to citizenship for Dreamers.

Bullock's record on immigration is somewhat thin, but according to OnTheIssues.org, he was one of 11 governors who signed a 2017 letter expressing support for DACA and urging Congress to pass a legislative fix to protect the roughly 800,000 DACA recipients.

Under de Blasio's leadership, New York was one of several cities to sue the administration over Trump's plan to withhold funding from sanctuary cities. In 2017, he told CNN that Trump's executive order banning citizens of certain Muslim-majority countries from entering the U.S. was "un-American," and he's said on Twitter that he supports the DREAM Act.

It's almost inconceivable that immigration won't be a top issue in the 2020 election. And as evidenced by their wildly varying stances, the candidates have a lot of different ideas on how to approach it.

This article has been updated.