President Donald Trump is expected to name the Internal Revenue Service agent who investigated Hunter Biden as the acting head of the IRS, sources familiar with the matter said.

Gary Shapley, the IRS whistleblower who accused the Justice Department under President Joe Biden of granting his son, Hunter Biden, special treatment during a yearslong probe into his tax affairs, is expected to lead the agency -- at least in the short term, sources said.

"Gary is a long-tenured civil servant who has dedicated the last 15 years of his professional life to the IRS. Gary has proven his honesty and devotion to enforcing the law without fear or favor, even at great cost to his own career. He’ll be a great asset to the IRS as we rethink and reform this crucial organization," a spokesperson for the Treasury Department told ABC News.

In March, Treasury Secretary Scott Bessent promoted Shapley as a senior adviser, where he was focused on IRS criminal investigations.

-ABC News' Rachel Scott, Will Steakin and Katherine Faulders

Maryland Democrat Sen. Chris Van Hollen will travel to El Salvador on Wednesday to work to facilitate the release of Kilmar Abrego Garcia, the Maryland man who the Trump administration admits was mistakenly deported to El Salvador and is being held in the notorious prison CECOT.

Van Hollen made his announcement at a joint town hall with Congresswoman April McClain Delaney, telling constituents

"I don't even know if we announced this, but I am planning tomorrow to go to El Salvador to work to bring him home," Van Hollen said.

Van Hollen had requested a meeting with El Salvador's President Nayib Bukele during his visit to the White House on Monday. He has repeatedly called for the Trump administration to facilitate Abrego Garcia's release and return to the U.S.

In a video message on X on Friday, he said, "The family is traumatized. They’re worried of course minute to minute about what might happen to him in that notorious prison. The Trump administration needs to get him home."

-ABC News' Oren Oppenheim, Lauren Peller and Meghan Mistry

President Donald Trump signed a memorandum on Tuesday aimed at preventing undocumented migrants and other ineligible people from obtaining Social Security benefits.

The memorandum includes expanding the Social Security Administration’s fraud prosecutor program and creating a Medicare and Medicaid fraud prosecution program in 15 U.S. Attorney's Offices.

The memorandum also tasks the Social Security inspector general with investigating earning reports for those aged 100 or older with mismatched SSA records, to push back against identity theft.

-ABC News' Michell Stoddart, Molly Nagle and Hannah Demissie

President Donald Trump signed a memorandum that directs the federal government to leverage "modern technology" to evaluate environmental reviews and permits, according to the fact sheet about the action.

The memo directs agencies to make such applications online, leaving behind paper copies, and to form a plan to digitize the review process.

The White House said that current environmental review and permitting processes are "inefficient, unpredictable, and counterproductive to the growth of the American economy."

-ABC News' Michell Stoddart, Molly Nagle and Hannah Demissie