U.S. Federal Election Commission (FEC) Commissioner and Chair Ellen Weintraub said on Thursday she received a letter from U.S. President Donald Trump that purports to fire her but added that the action was illegal.

In a post on X, Weintraub attached the Jan. 31 letter signed by Trump which said: "You are hereby removed as a Member of the Federal Election Commission, effective immediately."

Since taking office last month, Trump, a Republican, has embarked on a massive government makeover, firing and sidelining hundreds of civil servants and top officials at agencies in his first steps toward downsizing the bureaucracy and installing more loyalists.

"There's a legal way to replace FEC commissioners," Weintraub, a Democrat, said in her post, adding "this isn't it."

"I've been lucky to serve the American people & stir up some good trouble along the way. That's not changing anytime soon." 

The FEC has more than 300 employees, with six commissioners at the top. The FEC's vice-chair, James Trainor, is a Republican.

Weintraub has served as a commissioner on the FEC since 2002, according to the FEC website. It says she has "served as a consistent voice for meaningful campaign-finance law enforcement and robust disclosure."

FEC commissioners are appointed by the president and confirmed by the U.S. Senate.

By law, no more than three commissioners can represent the same political party, and at least four votes are required for any official commission action, the FEC website says.