WASHINGTON — House Republicans, overriding their top leaders, voted on Monday to significantly curtail the power of an independent ethics office set up in 2008 in the aftermath of corruption scandals that sent three members of Congress to jail.

The move to effectively kill the Office of Congressional Ethics was not made public until late Monday, when Representative Robert W. Goodlatte, Republican of Virginia and chairman of the House Judiciary Committee, announced that the House Republican Conference had approved the change. There was no advance notice or debate on the measure.

The surprising vote came on the eve of the start of a new session of Congress, where emboldened Republicans are ready to push an ambitious agenda on everything from health care to infrastructure, issues that will be the subject of intense lobbying from corporate interests. The House Republicans’ move would take away both power and independence from an investigative body, and give lawmakers more control over internal inquiries.

It also came on the eve of a historic shift in power in Washington, where Republicans control both houses of Congress and where a wealthy businessman with myriad potential conflicts of interest is preparing to move into the White House.

Speaker Paul D. Ryan and Representative Kevin McCarthy of California, the majority leader, spoke out during the meeting to oppose the measure, aides said on Monday night. The full House is scheduled to vote on Tuesday on the rules, which would last for two years, until the next congressional elections.

In place of the office, Republicans would create a new Office of Congressional Complaint Review that would report to the House Ethics Committee, which has been accused of ignoring credible allegations of wrongdoing by lawmakers.

“Poor way to begin draining the swamp,” Tom Fitton, president of the conservative group Judicial Watch, said on Twitter. He added, “Swamp wins with help of @SpeakerRyan, @RepGoodlatte.”

Mr. Goodlatte defended the action in a statement on Monday evening, saying it would strengthen ethics oversight in the House while also giving lawmakers better protections against what some of them have called overzealous efforts by the Office of Congressional Ethics.

“The O.C.E. has a serious and important role in the House, and this amendment does nothing to impede their work,” the statement said in part.

But Representative Nancy Pelosi of California, the House minority leader, joined others who had worked to create the office in expressing outrage at the move and the secretive way it was orchestrated.

“Republicans claim they want to ‘drain the swamp,’ but the night before the new Congress gets sworn in, the House G.O.P. has eliminated the only independent ethics oversight of their actions,” Ms. Pelosi said in a statement on Monday night. “Evidently, ethics are the first casualty of the new…