Donald Trump supporters hold signs during a campaign rally at Four Seasons Arena on Thursday in Great Falls, Montana.

As Donald Trump took the stage at an event in Montana this week, the president animated the crowd with a new rallying cry.

“We protect Ice,” he said. “They protect us and we protect them.”

Trump repeated the new slogan to raucous cheers. The president was referring to Immigration and Customs Enforcement, a law enforcement agency within the Department of Homeland Security that bears the responsibility of carrying out his hardline immigration agenda.

It was the latest sign that Trump, whose administration has been roundly criticized for separating migrant parents from their children at the border, wished to seize on the politics of immigration in an election year that could tip the balance of the US Congress.

With the 2018 midterm elections looming in November, Trump has sought to advance the narrative that Democrats support the abolition of Ice. The outcome, the president claims, would result in “open borders” and crime flowing into the United States.

It is a familiar ploy – reminiscent of Trump’s fear tactics around immigrants in the 2016 presidential race – and one embraced wholeheartedly by the White House and the Republican National Committee. By Friday, Vice-President Mike Pence was paying homage to Ice at its headquarters in Washington.

“We are with you 100%,” he said. “Under President Trump, we will never abolish Ice.”

The politics surrounding Ice have elevated the agency and its utility to the forefront of the debate over America’s immigration system. For Trump, it has served as a vehicle to distract from his administration’s confusion thus far over how to reunite the nearly 3,000 children who have been separated from their parents at the US border as a result of his policies.

“I think that Republicans are talking about Democrats abolishing Ice a lot more than Democrats are talking about abolishing Ice,” said David Fitzgerald, co-director at the Center for Comparative Immigration Studies at the University of California, San Diego.

The issue garnered attention after Alexandria Ocasio-Cortez, a 28-year-old progressive activist, pulled off a stunning victory over Joe Crowley, one of the senior Democrats in the House, in last month’s New York primary. Ocasio-Cortez made abolishing Ice, the functions of which include detaining and deporting undocumented immigrants, a central tenet of her platform.

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‘This is the beginning’: Alexandria Ocasio-Cortez’s victory speech – video

Only a handful of the 242 Democrats in Congress, which includes two independents who caucus with the party, have called for abolishing Ice. The majority of Democrats who have commented on the subject have suggested reforming the agency and its focus.

The list of those calling for Ice to be abolished nonetheless includes at least some prominent Democrats, such as Senators Kirsten Gillibrand of New York and Elizabeth Warren of Massachusetts, both regarded as potential contenders for the 2020 presidential race. Gillibrand said she agreed with Ocasio-Cortez’s position of abolishing Ice, stating the agency had become “a deportation force”.

“We believe that we should protect families that need our help and that is not what Ice is doing today,” Gillibrand said. “And that’s why I believe you should get rid of it, start over, reimagine it and build…