Erin Schaff for The New York Times
WASHINGTON — Three newly empowered Democratic House committee chairmen, alarmed by statements over the weekend by President Trump about his former lawyer’s planned testimony before Congress, cautioned on Sunday that any effort to discourage or influence a witness’s testimony could be construed as a crime.
The warning, a stark and unusual message from some of Congress’s most influential Democrats, underscores the increasing legal and political peril facing Mr. Trump. Democrats are beginning their own investigations of him as the special counsel, Robert S. Mueller III, appears to move toward a conclusion in his investigation into the Trump campaign’s ties to Russia and potential obstruction of justice by Mr. Trump.
In a Fox News interview on Saturday night, Mr. Trump accused the former lawyer, Michael D. Cohen, of lying about him to win leniency from federal prosecutors and spoke cryptically of the existence of damaging information against Mr. Cohen’s father-in-law. Mr. Cohen, who has been sentenced to three years in prison, has accused Mr. Trump of directing him to make illegal hush payments during the campaign.
“Our nation’s laws prohibit efforts to discourage, intimidate or otherwise pressure a witness not to provide testimony to Congress,” the chairmen wrote. “The president should make no statement or take any action to obstruct Congress’s independent oversight and investigative efforts, including by seeking to discourage any witness from testifying in response to a duly authorized request from Congress.”
The message seemed to imply that if Democrats in the House were to ever try to build an impeachment case against Mr. Trump, attempts to interfere with their work could be used as evidence.
One of the chairmen who signed the letter, Representative Elijah E. Cummings of Maryland, who leads the Oversight and Reform Committee, announced last week that Mr. Cohen would testify publicly for the first time next month about his work on behalf of Mr. Trump. The hearing promises to be a blockbuster session that could further erode Mr. Trump’s public image and clarify the extent of his legal exposure.
In August, Mr. Cohen pleaded guilty in federal court in Manhattan to tax fraud, making false statements to a bank and a campaign finance violation. He later pleaded guilty to an additional charge of lying to Congress about how long negotiations for a Trump Tower project in Moscow went on in 2016. He acknowledged that Mr. Trump’s associates pursued the project well into 2016, as the Kremlin was escalating its efforts to interfere in the American election on…