White House counselor Kellyanne Conway speaks at the Values Voter Summit of the Family Research Council in Washington, DC, U.S. October 13, 2017. REUTERS/James Lawler Duggan

WASHINGTON (Reuters) - The former head of a U.S. government ethics watchdog said on Wednesday he had filed a complaint claiming senior White House adviser Kellyanne Conway violated a law barring executive branch employees from engaging in political activity when she spoke on television against a Democratic candidate for the U.S. Senate.

Conway, in an interview on Fox News Channel on Monday, railed against Doug Jones, the Democratic candidate in the Dec. 12 special election for an Alabama seat in the U.S. Senate.

“Doug Jones in Alabama? Folks, don’t be fooled. He’ll be a vote against tax cuts,” Conway said. Jones’s Republican rival, Roy Moore, has been accused of pursuing teenage girls when he was in his 30s.

Walter Shaub, who stepped down as director of the Office of Government Ethics in July, said in a Twitter post: “I have filed a complaint with the U.S. Office of Special Counsel, which investigates Hatch Act violations.”

The 1939 Hatch Act prohibits federal employees from using their official authority to influence an election.

White House spokesman Raj Shah said: “Ms. Conway did not advocate for or against the election of a candidate, and specifically declined to encourage Alabamans to vote a certain way.”

Conway came under criticism from the ethics office in February when she publicly endorsed fashion products sold by President Donald Trump’s daughter Ivanka Trump.

Shaub, then head of the ethics office, wrote a letter to the White House in March voicing concern about the White House decision not to discipline Conway.

Shaub, who had clashed with the Trump administration over its business entanglements, has joined the Campaign Legal Center, a Washington-based nonpartisan group advocating for democratic reform.