A long-serving Republican appointee to the Federal Election Commission announced his resignation Monday, leaving the polarized panel without a four-person quorum to conduct business for the first time in 11 years. 

Matthew Petersen, who has sided with his GOP colleagues in favor of less regulation of the election process, will leave the FEC on Aug. 31. He did not specify a reason for his departure in his resignation letter to President Trump. 

“The work of a Commissioner is challenging because it involves taking actions that impact the free speech rights of the American people,” Petersen said in a statement Monday. “For this reason, I take satisfaction in having fulfilled my obligation to safeguard First Amendment interests while faithfully administering and enforcing the federal campaign finance laws.”

Petersen has served as FEC commissioner since President George W. Bush appointed him in 2008, beyond his six-year tenure. After serving as chairman in 2010 and 2016, he almost left the panel when Trump nominated him to the federal judiciary in 2017.

But he withdrew from consideration after struggling to answer questions about legal procedure during his confirmation hearing.before the Senate Judiciary Committee

Without Petersen, the six-member panel is left with just three commissioners — one Republican, one Democrat and one independent — who are all serving expired terms. The seats formerly held by Democratic appointee Ann Ravel and Republican appointee Lee Goodman have remained vacant for years. 

Four votes are required to take official action, such as enforcing regulations, issuing advisory opinions or approving audit reports. By law, no more than three of the commissioners can belong to the same political party.

The lack of a quorum will further complicate the ability of the FEC — which has long been ideologically split — to monitor compliance with election law as the 2020 campaign is ramping up.

“It’s never a good time for the commission not to have a functioning body,” said Kenneth Gross, a former associate general counsel for the FEC. “But we are approaching a federal election year and there may be additional matters that are coming up at this time.”

The depleted panel puts pressure on Trump to fill the vacant positions and make good on his campaign promise to address what he called a “rigged” campaign finance system

The White House did not respond to questions Monday about how it plans to address the empty FEC seats.

According to a senior GOP Senate aide, there are discussions about nominating a slate of six appointees and remaking the ­panel.

To do that, Senate Minority Leader Charles E. Schumer (D-N.Y.) and Senate Democrats “must replace the two longtime Democratic holdovers,” said the aide, who spoke on the condition of anonymity to talk freely about ongoing discussions. “A clean slate of members will go a long way toward fixing some of the perceived dysfunction at the Commission.”

“Congress should address this issue quickly because we need a fully functioning FEC,” a Schumer aide said in an email Monday.

Since taking office, Trump has nominated one person to the FEC: Texas attorney James E. “Trey” Trainor III, who was tapped in September 2017. The Senate has not held a confirmation hearing.