The nation's chief elections watchdog agency effectively shuts down on Saturday because it will no longer have enough members to legally meet and conduct business, prompting concern about whether the Federal Election Commission will be able to oversee how money is spent in elections and determine if campaigns are following the law.

With the resignation of Matthew Petersen, a Republican who served as the panel's vice chairman, taking effect on Aug. 31, the six-member FEC cannot reach its statutory four-member quorum, and critics argue that will leave the agency largely toothless ahead the 2020 elections.

"I think it's going to be a crisis in the electoral process," Ann Ravel, a Democrat and former commission chair whose seat is still unfilled after she resigned in 2017, told NBC News on Friday.

The terms of the commission's three current members — Democrat Ellen Weintraub, Republican Caroline Hunter and independent Steven Walther — have expired and they are currently on holdover status.

Weintraub, who serves at the commission's current chair, issued a statement on Monday saying "the United States' election cop is still on the 2020 campaign beat" and that its "most important duties will continue unimpeded." She added that the commission will continue to review previously authorized investigations and process complaints; however, it will be unable to vote on matters, conduct enforcement, such as imposing fines on violators, and pass rules until a quorum is restored.

Weintraub urged President Donald Trump and Senate Majority Leader Mitch McConnell, R-Ky., to fast-track confirmations of additional FEC members.

Republican commissioner Lee Goodman resigned in 2018, which at the time left the agency with four members. Trump has nominated Republican lawyer James Trainor III to the FEC several times but he has not yet been confirmed.

Now, Ravel said, Petersen's departure severely weakens the agency because it cannot meet to perform oversight over elections, such as open investigations, enforce campaign finance law, perform audits and launch litigation, among other functions.

"Yes, people are still going to file their campaign requirements of the contributions to the campaign and their expenditures,” Ravel said. "However, they also know that if there is no possibility of enforcement or even an audit being done that is going to be the subject of enforcement in which someone would be penalized there is no reason for them to follow the law."

David Simon, an attorney for the nonpartisan watchdog group Democracy 21, said that because of the resignation and lack of a quorum "the FEC will regress from a dysfunctional agency to one that, as a practical matter, ceases to function at all."

Ann Ravel, Chair of the Federal Election Commission, poses in her office at the FEC on July 17, 2015 in Washington. Bill Clark / CQ Roll Call via AP file

Ravel noted that the agency has garnered a reputation for being somewhat ineffective due in part to the requirement that the panel cannot have more than three members of the same political party, which she said has led to a deadlock. However, she stressed its role is in the election process is crucial.

"The whole point of campaign finance law is to ensure trust in the electoral process and give information to the voters so they know how to vote and know that there is corruption in the system — and that's not going to be possible," she said.

Daniel Weiner, a former senior staffer at the FEC who is now an attorney at the Brennan Center for Justice, said on Friday that oversight will "grind to a halt," a potentially serious problem in the face of the growing threat of foreign election interference.

"The FEC is one of the frontline agencies that is supposed to deal with the threat of foreign interference," he said.

The commission also went dark in 2008 for six months, which Weiner said led to an enormous backlog after the agency regained quorum.