WASHINGTON — Speaker Paul D. Ryan contradicted President Trump’s assertions of a broad conspiracy by federal law enforcement on Wednesday, joining other lawmakers in saying that the F.B.I. did nothing wrong by using a confidential informant to contact members of the Trump campaign as it investigated its ties to Russia.
And he said that Mr. Trump should not try to pardon himself, despite the president’s assertion two days earlier that he has the power to take such a step.
“I don’t know the technical answer to that question, but I think obviously the answer is he shouldn’t,” Mr. Ryan told reporters. “And no one is above the law.”
Mr. Ryan’s warning was the latest indication that the president is beginning to face trouble on Capitol Hill, where members of his own party are showing small signs of resistance. From international trade and China to immigration and the conduct of his cabinet, serious dissent from at least some Republicans is beginning to boil over.
At the forefront is an effort by Senators Bob Corker of Tennessee and Patrick J. Toomey of Pennsylvania to try to attach legislation to a must-pass defense policy bill that would require Mr. Trump to petition Congress for approval to impose national security tariffs, like those the White House has imposed on steel and aluminum produced in Canada, Mexico and Europe.
More than a half-dozen Republican senators have signed on to the amendment, and a small group of Republicans decamped Wednesday to the White House to try to navigate tensions with a protectionist president who has drastically departed from his party’s traditional embrace of free markets.
“I think this is a very bad idea, Mr. President,” Mr. Toomey said on the Senate floor. “I think it is a very bad path to be going on, very bad policy.”
Some Republicans are just as furious about Mr. Trump’s efforts to lift sanctions on a Chinese telecommunications company, ZTE. Last month, the House passed a bill that would prevent the administration from easing restrictions on the company, and the Senate Banking Committee approved a similar amendment that would prevent the president from modifying penalties on Chinese telecom companies that had violated American law in the past year.
On immigration, almost two dozen House Republicans are demanding votes on legislation that would help young immigrants brought to the country illegally as children, but are balking at the president’s get-tough demands on other immigration matters. And Iowa’s senators, Charles E. Grassley and Joni Ernst, both Republicans, came out swinging this week against the Environmental Protection Agency administrator, Scott Pruitt, whom Ms. Ernst called “as swampy as you get.”
But for Republicans, no issue has consumed more oxygen than the Justice Department inquiry into Russian interference in the 2016 election. Mr. Trump has seized on the disclosure of the use of an informant to claim, without evidence, that federal law enforcement officials had improperly placed a “spy” in his campaign “for political purposes.” He demanded a Justice Department inquiry of the matter and named the matter “SPYGATE” in repeated posts on Twitter. Mr. Ryan became the highest-ranking Republican to throw cold water on that interpretation, which Democrats and former high-level law enforcement officials have claimed is part of an unrelenting effort to discredit the open investigation into Mr. Trump and his campaign. Mr. Ryan backed Representative Trey Gowdy, Republican of South Carolina, who led the House’s politically charged investigation into the 2012 attack in Benghazi, Libya, but infuriated some Republican partisans by rebuffing Mr. Trump on “Spygate.”
“Chairman Gowdy’s initial assessment is accurate, but we have more digging to do,” Mr. Ryan told reporters at a news conference on Wednesday.
The comments appeared to be the latest sign that an uneasy truce between the party’s two most powerful figures might be fraying once more, and now that Mr. Ryan has announced he is not running for re-election. Despite a burst of Republican policy achievements — including a $1.5 trillion tax cut — the two men have more often than not appeared to embody two entirely independent Republican parties.
Mr. Trump has railed against free trade, immigration and Republican efforts to cut Social Security and Medicare, while veering toward the conspiratorial. Mr. Ryan, a Wisconsin conservative a generation younger, still speaks of trying to broaden the Republican Party’s appeal to minorities and has fought to move the president away from protectionist policies and racially divisive messaging.
And while Mr. Trump has denounced the Russia investigation, and pulled much of the party along with him, Mr. Ryan has repeatedly insisted that the special counsel, Robert S. Mueller III, be allowed to finish his work.
Mr. Gowdy and Mr. Ryan were among a small group of congressional leaders briefed on the informant late last month by top officials from the F.B.I., Justice Department and the office of the director of national intelligence. The unusual meeting came after Mr. Trump intervened on behalf of Representative Devin Nunes, Republican of California and the chairman of the Intelligence Committee, who was demanding information related to the informant.
Mr. Ryan has encouraged Mr. Gowdy, a former federal prosecutor and one of the House Republicans’ most experienced investigators, to help calm tensions between Mr. Nunes and the Justice Department. The two sides have repeatedly clashed as Mr. Nunes, a close ally of the president’s, has demanded greater and greater access to delicate case files.
Democrats emerged from the highly secretive briefing saying that they had seen “no evidence to support any allegation that the F.B.I. or any intelligence agency placed a ‘spy’ in the Trump campaign, or otherwise failed to follow appropriate procedures and protocols.” But Mr. Gowdy was the first Republican to break ranks a few days later, when he said on Fox News that the agency had acted properly.
“I think when the president finds out what happened, he is going to be not just fine, he is going to be glad that we have an F.B.I. that took seriously what they heard,” Mr. Gowdy said.
He added, “I am even more convinced that the F.B.I. did exactly what my fellow citizens would want them to do when they got the information they got, and that it has nothing to do with Donald Trump.”
People familiar with the matter have said that the informant was an American academic and veteran of Republican administrations who was to trying to glean information about what several campaign aides knew about the Russian efforts to hack into Democratic emails.
Senator Richard M. Burr, Republican of North Carolina and the chairman of the Senate Intelligence Committee, also put his support behind Mr. Gowdy’s analysis on Wednesday, after Mr. Ryan’s remarks. Mr. Burr had been silent after participating in the confidential briefing on the matter in late May.
Mr. Trump’s and Mr. Nunes’s conservative allies, who have not been briefed on the matter by law enforcement or intelligence officials, have publicly disagreed with Mr. Gowdy, claiming that the F.B.I. and the Justice Department had essentially pulled wool over the eyes of the South Carolina Republican.
Mr. Nunes, for his part, appeared to dismiss the importance of Mr. Gowdy’s statements in an interview on Sunday.
“Mr. Gowdy loves the F.B.I. and the Department of Justice,” Mr. Nunes said.
Still, Mr. Nunes signaled Sunday that he would like to bring the episode to a close. Speaking on Fox News, he said that he expected the Justice Department to share additional information and documentation with him this week.
“Just provide us all the documents, everything we’re asking for and let us comb all the way through it, and we’ll issue a letter on Friday and we’ll be done with this,” Mr. Nunes said.
Mr. Ryan’s warning on a “self-pardon” reflected other Republican concerns. Senator Mitch McConnell of Kentucky, the majority leader, cast the issue of Mr. Trump pardoning himself in similar terms on Tuesday.
“He obviously knows that would not be something that he would or should do,” Mr. McConnell said.