In 2016, Donald Trump promised to build a wall. This time around, he’s got a new campaign pledge: rounding up millions of undocumented immigrants — using the military, if necessary, and potentially holding them in detention camps.

“If I win you will have the largest deportation operation in American history, starting at noon on Inauguration Day, 2025,” Trump said in a speech in Asheville, North Carolina in August.

The deportation plan would face logistical and legal challenges. But Trump has whipped up support for his agenda by demonizing migrants with a stream of exaggerations, distortions and lies.

He has made the baseless claim, for instance, that migrants are being funneled into the country from foreign prisons and mental institutions. At the debate with Kamala Harris on Sept. 10, he repeated the debunked internet rumor that migrants were eating residents’ pets in Springfield, Ohio.

Fear-mongering aside, illegal border crossings did reach record levels under President Biden, sparking a crisis in places like New York, where spending on migrant services could top $11 billion statewide by next summer.

Mayor Eric Adams blamed the migrant crisis when he proposed major budget cuts last year. “This issue will destroy New York City,” he said at a town hall.

Now immigration is front and center in New York’s Congressional swing districts, where Republicans have followed Trump’s lead, taking a hard line on the issue. But New York Democrats, too, have shifted to the right, talking tough on the border.

Harris now talks up her background as a prosecutor in the border state of California. “I’m the only person on this stage who has prosecuted transnational criminal organizations,” she said during the debate.

After visiting the border last month, Harris gave a speech promising to clamp down on illegal immigration.

“Those who cross our borders unlawfully will be apprehended and removed and barred from re-entering for five years,” she told a crowd in Douglas, Arizona.

She has endorsed Biden’s executive order from June, which put new restrictions on asylum. Border crossings have since plummeted, easing the crisis in New York City, which is now closing the migrant center on Randall’s Island.

Harris also says she’ll bring back a tough bipartisan border security deal that Trump helped thwart.

But Trump blames Harris for the migrant influx. He refers to her as the border czar, though in fact her role under President Biden was to address the root causes of migration.

Trump also promises to revive policies from his first term: the travel ban that applied mostly to majority-Muslim countries; the “Remain in Mexico” policy keeping asylum seekers out of the U.S. while awaiting hearings; and Title 42, which bars immigrants on public health grounds.

He claims without evidence that migrants are carrying highly contagious diseases.

Trump has also proposed ending birthright citizenship for those born in the U.S. to undocumented parents, a move most legal experts agree is unconstitutional.

Unlike Trump, Harris has also talked about new pathways to citizenship for some immigrants, include so-called Dreamers, who were brought to the U.S. as children by undocumented parents.