WASHINGTON — President-elect Donald Trump’s meetings with CEOs seeking federal approval for major mergers are raising red flags for ethics lawyers concerned that about the possible erosion of a firewall between the regulators tasked with approving the billion-dollar deals and the White House.

Trump met this week with the heads of German chemical company Bayer and seed and herbicide giant Monsanto, who made their case for their $57 billion merger. The deal would likely need to be approved by Trump’s choices to lead antitrust enforcement at the Justice Department. On Thursday, Trump sat down to discuss jobs with the chief executive of AT&T, which is trying to acquire Time Warner.

Presidents typically keep their distance from such reviews, so as not to appear to be exerting political influence on a regulatory process intended to evaluate the impact a merger could have on competition and consumers. Trump’s closed-door sessions suggest the incoming president may be less worried with appearing to be close to pending deals that require government approval.

“While it’s true the Department of Justice is under the executive branch, it’s not appropriate for the president to make that regulatory decision — and certainly not for political considerations,” said Bruce Green, a law school professor at Fordham University who specializes in ethics.

Green equated the meetings to a 2016 campaign controversy: Bill Clinton’s conversation with Attorney General Loretta Lynch on the Phoenix airport tarmac at a time when the Justice Department was looking into Hillary Clinton’s use of a private email server.