WASHINGTON, Feb 29, 2024 (BSS/AFP) - President Joe Biden and Donald Trump will pay dueling visits to the US-Mexico border Thursday as they try to win over voters on one of the most divisive issues of November's presidential election.

The showdown in Texas comes as record numbers of migrant crossings into the United States create a major threat to Biden's chances of preventing a Trump comeback.

Democrat Biden will meet border patrol officers and law enforcement agents in Bronwnsville, Texas, while Republican Trump heads to Eagle Pass, about 300 miles (480 kilometers) to the west.

Biden has sought to defuse the politically toxic issue by blaming Republicans in Congress for failing to back his reforms to America's broken immigration system.

White House Press Secretary Karine Jean-Pierre said that in Brownsville Biden would deliver remarks to call highlight the need for Republicans to "get that done."

In a statement, the White House said he would tell them to "stop playing politics and to provide the funding needed for additional US Border Patrol agents, more asylum officers, fentanyl detection technology and more."

But for Trump a hard anti-immigration stance has been central to his political identity for years, and he has pledged the biggest ever US deportation program if he returns to the White House.

"No country can sustain what is happening to our country," the former president told the Conservative Political Action Conference (CPAC) in Washington earlier this month.

- 'My good friend' -

Trump added that migrants were "killing our people, they're killing our country" -- echoing the increasingly far-right rhetoric that saw him describe migrants last year as "poisoning the blood" of the United States.

The split-screen moment less than eight months before Americans go to the polls highlights the high-stakes of the border issue as Biden, 81, and Trump, 77, head for a rematch.

Biden insisted earlier this week that he hadn't deliberately planned the clash of schedules with bitter rival Trump, whose rhetoric the Democrat has likened to the Nazis.

"I planned for Thursday, what I didn't know was that my good friend apparently is going," he told reporters during a visit to an ice cream shop in New York.

Biden also refused to say whether he would meet with migrants after criticism that he did not do so on a previous visit.

Republicans blame Biden's policies favoring the right to asylum for the flow of migrants, while the White House says that Trump's party is deliberately sabotaging a bipartisan attempt to find a solution.

The border issue has also become tangled up in a bitter row over US aid for Ukraine's fight against the Russian invasion, with Republicans insisting migration must be tackled before they unblock funding.

Public concern about illegal immigration is meanwhile higher under Biden than it was under the last two administrations, with a majority now supporting a border wall of the kind Trump started building, according to a new poll by Monmouth.

A poll by US broadcaster NBC in February showed Trump leading Biden by 30 points on the issue of immigration.