A nonpartisan watchdog group in an ethics complaint Wednesday asked Congress to investigate how Rep. Devin Nunes (R-Calif.) is paying for several ongoing lawsuits against critics.

In its complaint to the Office of Congressional Ethics, the Campaign Legal Center notes Nunes's annual congressional salary of $174,000 would likely not cover the costs of the various suits, indicating that he is either receiving free or discounted legal services or working on contingency with an attorney, all of which would require him to disclose the assistance.

Nunes has yet to file a legal expense fund with the Office of Congressional Ethics.

"Representative Nunes's overt involvement with the highly-publicized lawsuits threatens to establish a precedent that the Legal Expense Fund regulations no longer apply to Members," the complaint states.

"Although Representative Nunes is entitled to legal representation and he may pursue any legal action to protect and defend his interests, he must comply with House rules," it continued. "An [Office of Congressional Ethics] investigation will preserve Representative Nunes's legal right to counsel while upholding well-established House rules and precedent."

Defendants in Nunes's lawsuits include Twitter, CNN, McClatchy and two anonymous Twitter accounts that have mocked him.

The complaint also claims that even if Nunes was paying Virginia attorney Steven Biss based on contingency - meaning that should Nunes win his cases, Biss would get paid by taking a percentage the resulting award - Biss has also sent two letters demanding apologies for criticisms from Rep. Ted Lieu (D-Calif.) and Nunes's 2017 opponent Andrew Janz.

"Mr. Biss sent a letter to Representative Lieu threatening to bring an ethics complaint against him," the complaint reads. "An ethics complaint will not result in a monetary award that could support payment under a contingency fee agreement."

The complaint argues Nunes should disclose any contingency arrangement under House ethics rules to ensure he is not in violation of rules on gifts, citing a case in 2008 in which then-Rep. Jean Schmidt (R-Ohio) requested approval from the Committee on Ethics to pay for lawyers through contingency, which was denied.

The Hill has reached out to Nunes's office for comment.