Caroline Hunter, a member of the Federal Election Commission who regularly clashed with her fellow commissioners, resigned on Friday, according to a letter obtained by ABC News.
Hunter, a Republican, who was appointed by former President George W. Bush in 2008, regularly butted heads with FEC Commissioner Ellen Weintraub, a Democrat also nominated by former President Bush.
She will stay on with the FEC until July 3. The White House has already nominated Allen Dickerson, the legal director of the Institute for Free Speech, to take her place.
In her resignation letter, Hunter has some strong criticism for Weintraub, though she is not mentioned by name.
"The FEC would benefit greatly from new faces and fresh perspectives. It needs Commissioners who will respect the First Amendment, understand the limits of the FEC's jurisdiction, and remember that Congress established the FEC to prevent single-party control, with every significant decision requiring bipartisan approval," Hunter wrote.
"One Commissioner -- who has served for more than a decade past the expiration of her term -- routinely mischaracterizes disagreements among Commissioners about the law as 'dysfunction,' rather than a natural consequence of the FEC's unique structure, misrepresents the jurisdiction of the agency and deliberately enables outside groups to usurp the Commission's role in litigation and chill protected speech," she added. "The American people deserve better."
With Hunter's resignation, the FEC is again left with just three out of six commissioners, meaning that it is one vote short of the minimum four votes needed to act on any substantive matters.
The FEC was left in the same place with no enforcement power for nearly a year, after former Vice Chairman Matthew Petersen resigned from his position last August, until recently.
In May, the Senate finally confirmed President Donald Trump's appointee, Trey Trainor, a Texas election attorney, to fill one of the vacancies on the commission, restoring the quorum.
"It's keenly disappointing for the FEC to lose its quorum just a blink of an eye after we regained it," said Weintraub. "But of course I wish Caroline well in this and all her future endeavors."
The remaining members of the commission are Republican Chair Trainor, Democratic Commissioner Weintraub, and Independent Vice Chair Steven Walther.
Without the four-person quorum, it will not be able to initiate audits, engage in rulemaking, vote on enforcement matters or even issue an advisory opinion or hold meetings.
The commission will continue to perform its important day-to-day duties of making details of 2020 campaign contributions and expenditures available, and its enforcement arm will still review complaints and make recommendations to the commission on those matters.
Trevor Potter, president of Washington-based nonpartisan ethics group Campaign Legal Center and a former Republican chair of the FEC, called for a prompt replacement of Hunter to restore the quorum, saying her resignation has left "democratic elections with significantly less government oversight."
"A huge majority of voters are concerned about the enforcement of our campaign finance laws, and Hunter's resignation leaves their democratic elections with significantly less government oversight," Potter said in a statement. "Elections in 2016 and 2018 saw campaign finance violations including: illegal foreign spending, a lack of transparency around the sources of millions in election spending, and candidates working illegally with super PACs."
"Americans understand that the campaign finance system correlates directly to their families' quality of life," he continued. "The corruption of our democracy by unprecedented amounts of money in our elections from wealthy special interests diminishes the voices of average citizens. A strong and functional FEC is vital to protecting our democracy, fighting corruption, and holding politicians accountable for the campaign money they receive."
A source familiar with Hunter's thinking told ABC News that Weintraub's decision to let outside groups file lawsuits directly in federal court against other groups and individuals is something on which Hunter strongly disagreed with Weintraub.
"Fire alarms are sometimes housed in boxes labeled 'Break glass in case of emergency.' The Federal Election Campaign Act has such a box; it's the provision that allows complainants to sue respondents directly when the Federal Election Commission fails to enforce the law itself. In the 44-year history of the FEC, this provision has never been fully utilized. Today, I'm breaking the glass," Weintraub said in 2018.
This incident "took the dysfunction to a new level," the source explained.
Hunter served on the FEC for 12 years and as the commission chair three times and plans to join "the legal team of Stand Together, a philanthropic organization dedicated to tackling some of the biggest challenges of our times, including reforming the nation's criminal justice system, strengthening K-12 education, helping neighbors beat poverty and addiction, empowering everyone to find fulfilling work, and more," according to a press release.