U.S. President Joe Biden visited the U.S.-Mexico border on Sunday for the first time since taking office, tackling one of the most politically charged issues in the country as he prepares for a re-election bid.

Accompanied by Border Patrol agents, Biden toured a section of the wall that divides the two countries, a signature priority of his Republican predecessor Donald Trump, in an effort to demonstrate that he was taking the issue seriously.

Biden said on Thursday that his administration would tighten immigration enforcement by blocking Cuban, Haitian and Nicaraguan migrants at the border, expanding the nationalities of those who can be expelled back to Mexico.