Rep. Matt Gaetz filed a complaint against the Democratic chairman of the House Intelligence Committee in a move that could usher an end to a decadeslong bipartisan ethics détente.

The Florida Republican sent a letter to the 10-member bipartisan panel led by Rep. Ted Deutch, calling on the committee to investigate Rep. Adam Schiff over the California lawmaker's handling of impeachment proceedings against President Trump.

It’s rare for a lawmaker to file an ethics complaint against another member, in part because lawmakers are fearful of sparking retaliatory complaints.

House lawmakers have seldom filed ethics complaints, particularly across party lines, after the two sides agreed to end a partisan ethics war that consumed Congress more than two decades ago.

Since then, ethics investigations have typically been self-initiated by the committee or referred by an independent outside panel, the Office of Congressional Ethics, which was created by the House and can field complaints from groups and individuals not serving in Congress.

Gaetz wants the panel to investigate Schiff’s opening statement at the only public impeachment hearing so far, in which Schiff delivered a parody account of President Trump’s July 25 phone call with Ukrainian President Volodymyr Zelensky, which is at the heart of the impeachment proceedings.

Gaetz also wants Ethics to investigate Schiff’s past statements in which Schiff claimed to have knowledge of evidence Trump colluded with Russia ahead of the 2016 presidential election.

A two-year investigation by special counsel Robert Mueller did not charge Trump with colluding with the Russians, although Democrats say the Mueller report includes evidence of collusion.

And Gaetz wants the Ethics panel to look into Schiff’s decision to block Gaetz and other Republicans from the closed-door impeachment proceedings taking place in the Capitol basement.

Gaetz has tried to gain entry into the proceedings, which are limited to the House Intelligence, Foreign Relations, and Oversight and Government Reform Committees. The House parliamentarian has ruled that Gaetz and other lawmakers who do not sit on the three invited panels cannot attend the closed-door proceedings.

Gaetz said he should be allowed into the proceedings because he is a member of the House Judiciary Committee, which has handled impeachment investigations in the past.

“Chairman Schiff has abused his authority and seems to believe that the rules of the House of Representatives do not apply to him,” Gaetz said in a statement. “We cannot have a multi-tiered justice system in the United States or in the Congress. His egregious behavior must change immediately.”

The Ethics panel is unlikely to open a formal subcommittee hearing into Schiff’s actions.

But the panel will at least have to review the complaint and issue a statement, even if it dismisses it. His complaint will undoubtedly ratchet up the partisan discord in the House and could make it more tempting for Democrats to file complaints against GOP lawmakers they believe have broken House rules.

In his letter to the Ethics panel, Gaetz urged the committee, after it investigates the matter, “to make all appropriate referrals to the Department of Justice, for further investigation and prosecution.”

A Schiff spokesman hasn’t yet responded to a request for comment about the complaint.

Schiff’s opening statement, delivered during a Sept. 26 public hearing about the Ukraine call, generated bipartisan criticism.

"We've been very good to your country,” Schiff said, pretending to read the call transcript. “Very good. No other country has done as much as we have. But you know what? I don't see much reciprocity here. I hear what you want. I have a favor I want from you, though. And I'm going to say this only seven times, so you better listen good. I want you to make up dirt on my political opponent, understand? Lots of it. On this and on that.”

Gaetz is the subject of a House ethics inquiry that was first filed with the Office of Congressional Ethics by an outside Democratic political action committee that accused him of using his Twitter account and role in Congress to threaten Trump’s former lawyer, Michael Cohen.