WASHINGTON — Former deputy national security adviser Charles Kupperman will not appear for a scheduled deposition Monday before three House congressional committees involved in leading the impeachment inquiry against President Donald Trump, congressional leaders said Monday.

The White House is trying to block his appearance, and Kupperman, who worked under former national security adviser John Bolton, filed a lawsuit Friday asking a federal judge to rule on whether he must testify under a congressional subpoena.

House Oversight Committee ranking member Jim Jordan, R-Ohio, told reporters on Capitol Hill on Monday that Kupperman will wait to testify until the judge rules on the subpoena.

Speaking to reporters moments later, House Intelligence Committee Chairman Adam Schiff, D-Calif., told reporters it was "deeply regrettable" that Kupperman was a "no-show."

"He was compelled to appear with a lawful congressional subpoena," Schiff said. "Witnesses like Dr. Kupperman need to do their duty and show up."

Kupperman's refusal to appear "may warrant a contempt proceeding against him," he added.

"I think we can infer from the White House opposition to Dr. Kupperman's testimony that they believe that his testimony would be incriminating of the president," Schiff said. "It is also, I think, very plain additional and powerful evidence of obstruction of Congress and its lawful function, by the president, that yet again, and even after a court decision affirming the right of Congress to proceed with this impeachment inquiry, the White House has obstructed the work of a co-equal branch of government."

Three Democratic committee chairs alleged in a letter to Kupperman's lawyer on Saturday that the ex-deputy national security adviser was simply trying to delay the deposition.

In the letter, Schiff, Foreign Affairs Chairman Eliot Engel, D-N.Y., and House Oversight Chairwoman Carolyn Maloney, D-N.Y., said Kupperman's lawsuit was "lacking in legal merit" and alleged that it was "apparently coordinated with the White House."

They called the suit "an obvious and desperate tactic by the President to delay and obstruct the lawful constitutional functions of Congress and conceal evidence about his conduct from the impeachment inquiry" and said that a failure to cooperate with the subpoena would give greater weight to the obstruction case against the president.

Kupperman, a longtime associate of Bolton, has emerged as a key witness in the impeachment inquiry. House investigators believe he has firsthand knowledge of Trump's decisions regarding Ukraine.

Kupperman’s attorney responded late Saturday in a letter obtained by NBC News that said "it would not be appropriate for a private citizen like Dr. Kupperman to unilaterally resolve this momentous Constitutional dispute between the two political branches of our government."

Bolton told former White House official Fiona Hill that he wanted no part of Trump's effort to get Ukraine to investigate former Vice President Joe Biden and his son Hunter Biden as well as what has been described as a conspiracy theory involving the 2016 election, Hill told congressional investigators earlier this month, NBC News previously reported. Hill added that Bolton told her to report the situation to the top lawyer at the National Security Council.