WASHINGTON (Reuters) - White House senior adviser Kellyanne Conway defied a subpoena and failed to appear on Monday at a congressional hearing about allegations she violated federal law, prompting a Democratic threat to hold her in contempt of Congress.

White House adviser Kellyanne Conway speaks to reporters at the White House in Washington, U.S., July 9, 2019. REUTERS/Kevin Lamarque

The top White House lawyer directed Conway not to appear at the U.S. House of Representatives Oversight Committee hearing, arguing that current and former White House officials were “absolutely immune” from being required to testify before Congress, according to a letter released by the committee.

Past presidential administrations from both parties have adopted similar arguments, but some legal experts have said such immunity claims would be rejected by a judge if challenged in court.

Three weeks ago, Conway declined to appear voluntarily at a similar hearing before the committee, prompting it to vote 25-16 to subpoena her testimony. The committee wants to question her about allegations she violated the Hatch Act, a law that limits federal employees’ political activity.

The White House said in a statement that Monday’s hearing was part of a “purely political campaign to harass the President and his close advisers.”

President Donald Trump is stonewalling multiple congressional inquiries into him, his policies, family and business holdings.

House Oversight Committee Chairman Elijah Cummings said at Monday’s hearing that it was “clear-cut” that Conway was required to comply with the subpoena.

“We are not requiring her to testify about advice she gave the President or about the White House’s policy decisions,” Cummings said. “We are requiring her to testify before Congress about her multiple violations of federal law, her waste of taxpayer funds, and her actions that compromise public confidence in the integrity of the federal government.”

Cummings said that if Conway did not reconsider, the committee would convene a meeting on July 25 to hold her in contempt, a move that could lead to a lawsuit seeking to force her compliance.

The Office of Special Counsel (OSC), a U.S. government watchdog agency, last month recommended Conway be fired for repeatedly violating the Hatch Act by disparaging Democratic presidential candidates while speaking in her official capacity during television interviews and on social media.

Henry Kerner, a longtime Republican Party lawyer who runs the OSC, told last month’s committee hearing that Conway left him “no choice” but to recommend her termination because she had committed “at least 10 separate Hatch Act violations, expressed no remorse and continues to express disdain” for the law.

The White House has argued that the OSC has adopted a legally dubious interpretation of the Hatch Act that chills the free-speech rights of U.S. government employees.