Depending on how a handful of swing states choose in November, the next president will either target every undocumented immigrant in the country for deportation or provide millions with work permits instead.

Experts from all sides of the immigration spectrum say the policy gap between Donald Trump, who on Wednesday reaffirmed his support for a border wall and mass deportation, and Hillary Clinton, who has pledged to further integrate millions of undocumented immigrants into American society, is unprecedented in recent history.

“There will be no amnesty," Donald Trump said in a speech in Arizona. "Our message to the world will be this: You cannot obtain legal status or become a citizen of the United States by illegally entering our country."

In the same address, Trump called for a new “deportation task force” to root out criminals and for tripling the number of immigration agents tasked with removing immigration violators from the interior. He promised to cut off funding to “sanctuary cities,” immediately remove any undocumented immigrant arrested for a crime, and warned that “no one will be immune or exempt from enforcement.”

Hillary Clinton, by contrast, has pledged to pursue legislation creating a path to citizenship for qualifying immigrants in her first 100 days in office. Failing that, she has pledged to "go even further” than President Obama in using executive action to shield undocumented immigrants from deportations, and pledged she would not deport children or break up families.

“I do not have the same policy as the current administration does,” Clinton said during a Democratic debate in March. “I think it's important that we move to our comprehensive immigration reform, but at the same time, stop the raids, stop the round-ups, stop the deporting of people who are living here doing their lives, doing their jobs, and that's my priority."

Trump has said he would deport young undocumented immigrants without hesitation; Clinton has hired DREAMers to campaign jobs. Trump regularly brings parents whose children were killed by undocumented immigrants onstage at his rallies; Clinton brought undocumented immigrants onto the main stage of the Democratic National Convention in primetime. She’s also said undocumented immigrants should have access to the Affordable Care Act’s exchanges (though not its subsidies). Trump said in his speech Wednesday he would prioritize removing “public charges” who are “straining the safety net.”

“Trump really is talking about sealing off the country, closing off the border, and throwing out the key,” David Leopold, an immigration attorney supportive of recent immigration reform efforts, told NBC News. “It’s not hyperbole.”

Mark Krikorian, whose Center for Immigration Studies favors lower immigration levels, said Clinton had widened the gap by moving significantly to the left in recent years.

“These two are farther apart than any two I can remember,” Krikorian said.

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As recently as 2007, Clinton opposed issuing driver licenses to undocumented immigrants while running for president. Her journey towards championing the undocumented population paralleled the Democratic Party’s move as well, with interest groups like labor unions gradually moving from skeptics of immigration reform to champions.

Trump went through his own journey as well. After Mitt Romney lost the 2012 race running on a hardline enforcement position, Trump blamed the former nominee’s “maniacal” and “crazy” policy of self-deportation and suggested he might allow undocumented immigrants to stay in the country.

This choice couldn't be starker. pic.twitter.com/9msdztcXbE — Hillary Clinton (@HillaryClinton) September 1, 2016

The widening chasm comes just three years after Republicans and Democrats successfully passed a bipartisan reform bill in the Senate that would have have revised and expanded legal immigration, provided a path to citizenship for many of the estimated 11 million undocumented immigrants in America today, and instituted new enforcement measures. That effort was killed in the House by a populist uprising that presaged the party’s sharp turn to the right in the 2016 presidential race.

With the Clinton and Trump so far off now, it’s an open question whether there’s hope for another bipartisan effort akin to the 2013 bill or for substantial legislation in line with Trump’s enforcement-only plan.

If Clinton fails to pass a comprehensive immigration reform package, she would still have plenty of room to act. Obama’s 2014 proposal to grant temporary work permits to several million additional undocumented immigrants has been stymied by the courts, but that’s because the Supreme Court deadlocked 4-4 this year and deferred to a lower court’s decision. If Clinton appoints a new justice who decides a similar plan is legal, it could go forward.

Mexico will pay for the wall! — Donald J. Trump (@realDonaldTrump) September 1, 2016

Trump could face tougher challenges enacting his agenda on his own. While he has pledged to undo Obama’s executive orders protecting DREAMers and other undocumented immigrants from deportation, he would need Congress to approve funding for his border wall, expand the number of officers deporting immigrants, and add new judges and detention centers to process their cases.

Congress would also have to approve his proposal to institute a mandatory e-verify system to detect illegal workers as well as other security measures like a nationwide system to track visa overstays. Versions of these measures were included in the Gang of Eight bill, but it’s unlikely Democrats would go along with them outside of a comprehensive package that included a path to legal status.

Some pro-reform Republicans, Democrats, and activists have predicted a Trump loss would again send Republicans back to the negotiating table out of fear the issue was dragging down the national party. Polls have consistently shown Trump’s no-exceptions deportation policy is a minority view even within his own party: 77 percent of voters backed a path to legal status over deportations in a Fox News poll this week and pluralities of Republican primary voters said the same in nearly every state with exit polls this year.

“Republican Party won't win WH until after some comprehensive immigration is passed & in rear window,” former Romney strategist Stu Stevens tweeted on Thursday. “It's math.”

But there could be complications. Among them, a growing divide over legal immigration between the parties as Trump increasingly casts foreign workers as competition for American jobs and talks up new restrictions on visas.

While at times a contentious issue between labor and business groups, politicians in both parties largely were comfortable supporting an expanded legal immigration framework as part of a deal during the 2013 immigration debate. Even arch-conservative Senator Ted Cruz, for example, proposed a 500 percent increase in H1B worker visas while opposing the broader bill.

That bipartisan assumption has been called into question thanks in part to a series of stories on alleged abuses involving H1B visas and a rise in populist outlets like Breitbart that put more emphasis on reducing legal immigration. Even before Trump arrived on the scene, presidential candidates like Rick Santorum and Wisconsin Governor Scott Walker began talking about potentially reducing overall immigration. Later in the race, Cruz renounced his old calls for more immigration and instead called for a freeze on total immigration levels until the labor participation rate rose.

Trump himself has called for an indefinite “pause” on issuing new green cards for workers in which businesses would have to prove they were unable to fill jobs with American employees. Immigration activists say they’re especially concerned by his proposed Muslim ban and a related call to halt immigration from countries plagued by terrorism. Depending on how it’s defined, such a move could block entry from countries like India, France, Israel, or the Philippines that have deep ties with the United States.

“I think that with Trump, what we have seen is the most radical restrictions on the legal immigration system in at least the last century,” said Todd Schulte, the president of pro-immigration advocacy group FWD.us. “With Clinton we've seen a big contrast to that and hope she will continue to spell out her plans to create a legal immigration system with a focus on allowing the best and the brightest to come here.”

On the Democratic side, Clinton has promised to “staple” a green card to masters degrees and PhDs in the science, technology, engineering, and mathematics fields and has called for the creation of visas for foreign entrepreneurs. But she told Vox in July that issues like adding more visas for tech jobs should come second to resolving the fight over illegal immigration, sparking concern from groups like the Chamber of Commerce that favor such changes.

Clinton has said less about her view on immigration limits overall, but has spoken in general about the benefit immigrants provide to America. Legal immigration never came up much during the Democratic primary, but Bernie Sanders — echoing populist rhetoric in both parties — notably warned that higher immigration levels depress wages.

"There is a reason that Wall Street likes immigration reform," Sanders told NBC News in July of last year, also noting the backing of the Koch Brothers and the U.S. Chamber. "What I think they’re interested in is seeing a process by which we can bring low-wage labor into this county."

Ironically, while illegal immigration dominates the political conversation, public opinion on legal immigration is much more evenly split. Gallup, which polls the issue annually, has long found a plurality of Americans favor either decreasing or maintaining current immigration levels rather than increasing them, although support is rising for the latter option. It's possible this side of the immigration debate becomes a bigger issue regardless of who wins in November.