US President Joe Biden to visit border town of Brownsville, Texas as Donald Trump heads to Eagle Pass, Texas.

US President Joe Biden and Donald Trump, his likely Republican opponent in the November election, will make separate visits to the US-Mexico border on Thursday as immigration has become a key issue for voters.

Biden, who has been on the defensive on the issue in recent months, will use a visit to the border town of Brownsville, Texas, to highlight how Republican lawmakers rejected a bipartisan effort to toughen immigration policies on Trump’s orders.

Biden will meet border patrol agents and customs and law enforcement officials and deliver remarks on Thursday.

“He is going because it’s important to highlight that Republicans are getting in the way here,” said White House press secretary Karine Jean-Pierre.

Biden took office in 2021 promising to reverse the hardline immigration policies of Trump, but has since toughened his own approach.

Under pressure from Republicans who accuse him of failing to control the border, Biden called on Congress last year to provide more enforcement funding and said he would “shut down the border” if given new authority to turn back migrants.

Biden will be joined by Homeland Security Secretary Alejandro Mayorkas, whom Republican legislators earlier this month narrowly voted to impeach over his handling of the border. The Democratic-led Senate, however, is unlikely to vote to remove Mayorkas from office.

Trump, who as president from 2017 to early 2021 considered a tough border stance to be a signature issue for him, has accused Biden of bungling border issues. He will visit Eagle Pass, Texas, where arrivals have posed a problem for authorities in recent months.

Karoline Leavitt, national press secretary for the Trump campaign, called the border a “crime scene” in a statement and said the former president on the visit will outline a plan to “secure the border immediately upon taking office”.

A Reuters-Ipsos poll from January 31 found rising concern among Americans about immigration, with 17 percent of respondents listing it as the most important problem facing the US today, up sharply from 11 percent in December. It was the top concern of Republican respondents, with 36 percent citing it as their main worry, above the 29 percent who cited the economy.

Trump will be joined by Texas Governor Greg Abbott, whose administration has been building a military “base camp” at Eagle Pass to deter migrants.

Eagle Pass remains a flashpoint in a heated partisan debate over border security even though the number of migrants caught crossing without papers into both there and Brownsville dropped sharply in January and February.

The number of migrants caught crossing the US-Mexico border without papers hit a monthly record of 250,000 in December, but dropped by half in January, a trend US officials attribute to increased Mexican enforcement and seasonal trends.

Abbott, a Republican, has deployed thousands of National Guard troops and laid concertina wire and river buoys to deter illegal immigration through a program called Operation Lone Star.

Immigration enforcement historically has been the purview of the federal government, and Abbott’s actions have sparked legal and political standoffs with the Biden administration and immigrant rights activists.