US President Donald Trump's adviser Kellyanne Conway will not testify before the House of Representatives Oversight Committee on her alleged violations of the Hatch Act, the White House has told the panel's chairman.
The 1939 Hatch Act prohibits executive branch employees from engaging in some political activities.
Conway was requested to testify before the committee this week.
"In accordance with long-standing precedent, we respectfully decline the invitation to make Ms Conway available for testimony before the Committee," White House legal counsel Pat Cipollone told Democratic Representative Elijah Cummings in a letter on Monday.
The Oversight Committee said it would vote on a potential subpoena if Conway does not testify before lawmakers on Wednesday.
The hearing was scheduled after the Office of Special Counsel, a US government watchdog agency, earlier this 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.
Trump has said he would not fire Conway, 52, a former political pollster who became Trump's campaign manager in 2016 and the first woman to oversee a winning US presidential campaign.
House Democrats have been frustrated by the Trump administration's stonewalling of their efforts to hold senior officials to account. Treasury Secretary Steven Mnuchin, Commerce Secretary Wilbur Ross, Attorney General William Barr and other officials have defied subpoena requests from Democratic-led House panels in recent months.
