Representative Matt Gaetz has filed an ethics complaint against ex-House Speaker Kevin McCarthy for allegedly assaulting a fellow Republican.
Representative Tim Burchett of Tennessee said Mr McCarthy "elbowed" him in the back while he was speaking with a reporter in Congress on Tuesday.
Long-term adversaries of Mr McCarthy's, the pair led efforts to oust him from the Speaker's office in October.
Mr McCarthy said the alleged altercation was accidental.
The incident, described by NPR journalist Claudia Grisales who witnessed the interaction, came just hours before Mr McCarthy's replacement, new House Speaker Mike Johnson, passed his first major legislative test, a full House vote on his plan for avoiding a government shutdown.
"He's a bully with $17m and a security detail," Mr Burchett said of the former Republican leader. Mr McCarthy later told reporters the physical contact was accidental.
"If I would hit somebody, they would know I hit them," the Californian congressman told reporters.
But in his ethics complaint, Mr Gaetz said Mr Burchett described the assault as a "sucker punch" and a "clean shot to the kidney".
The ultra-conservative argued in a letter that the incident deserved "immediate and swift investigation by the Ethics Committee".
"This Congress has seen a substantial increase in breaches of decorum unlike anything we have seen since the pre-Civil War era," he wrote in the complaint.
"The rot starts at the top," he added.
When informed of Mr Gaetz's complaint, Mr McCarthy replied "oh, good," before adding that "Ethics is a good place for Gaetz to be".
Mr Gaetz is himself the subject of an ongoing ethics investigation into allegations of sexual misconduct.
The Republican Party has been consumed by chaos for nearly two months, after eight right-wing Republicans - including Mr Burchett - voted to oust Mr McCarthy from his post.
According to Mr Burchett, Tuesday's run-in was the first time he had spoken to Mr McCarthy since voting against him last month.
Recounting the incident to reporters, Mr Burchett said he ran after the former Speaker.
"As he [Representative McCarthy] always did, he just denies it or blames somebody else," Mr Burchett said.
He said he would not be pressing charges.
"It's over as far as I'm concerned," he said. "I pray for him and hope he finds some happiness in his life."
