US President Donald Trump is facing widening opposition within his own party as Republican lawmakers in Congress, long reluctant to defy him, are showing a greater willingness to break ranks with the US president.

Just over the past week, multiple factions of Republicans in the Senate and House of Representatives have stepped forward to rebuke his war against Iran, reject $1 billion in funding tied to his White House ballroom, force a retreat on his $1.8 billion "anti-weaponization" fund, and block his legislation on domestic spying.

The House also defied Trump by passing a bill on Thursday to provide aid to Ukraine and impose new sanctions on Russia, a measure that seems destined for a veto by the president.

Republicans and Democrats are skeptical that Trump faces an actual revolt. But a growing coalition of Republicans is showing a willingness to break with him, including those Trump has personally helped to drum out of office, and could pose a threat to his most ambitious initiatives between now and Election Day.

"I think what you're seeing as you get closer to the election is that people are going to vote the way they think their constituents want them to," said Republican Senator Thom Tillis, who announced his retirement from the Senate last year after opposing the president's so-called One Big Beautiful Bill.

Democrats largely dismissed the idea, saying there has been no evidence that the party at large is willing to defy him on major issues.

"The people that are breaking with him are ones that were put out by Trump," said Senator John Fetterman, a Democrat who sometimes supports Trump-backed initiatives. "That actually demonstrates his absolute control over the party."

One White House official, speaking on condition of anonymity, chalked Republican dissent up to "election-year politics." "Not every single member will absorb the political cost on every single issue," the person said.

"While the media and Democrats attempt to sow nonexistent divisions, we look forward to continuing this close relationship to continue fulfilling President Trump's agenda," White House spokeswoman Abigail Jackson said.

For years, Republican lawmakers have shown public fealty to Trump by backing controversial cabinet picks, showing little or no resistance to his executive orders, and supporting his signature legislation despite misgivings about the ballooning deficit and cuts to the Medicaid healthcare program for low-income Americans.

Lawmakers and aides say frustration and resentment have grown since Trump opposed the reelection bids of Republican Senators Bill Cassidy and John Cornyn and endangered the Republican agenda in Congress with a series of badly timed announcements.

The inflection point came just before the US Memorial Day holiday, when Trump's decision to oppose the reelection of Cornyn and the announcement of his "anti-weaponization" fund forced Senate Republicans to abandon a $70 billion immigration enforcement funding bill and leave town in a mood of anger and frustration.

"That was kind of like a perfect storm of events," a Senate Republican aide said.

The Senate ultimately passed the immigration enforcement funding bill on Friday, and Republicans voted against a Democratic amendment to block the funding, even as some worry it could be used to pay January 6 Capitol rioters and other Trump political allies.

Trump appointed loyalist Bill Pulte to replace Tulsi Gabbard as a temporary Director of National Intelligence, even though key Republicans have misgivings.

Senator Mitch McConnell made it clear he would not back Pulte as a permanent DNI, saying the law required nominees with extensive experience. "No nominee who falls short of this requirement will earn my vote," he said in a statement.

Republican opposition on the floors of the House and Senate has been mostly symbolic to date.

Three electorally vulnerable Senate Republicans - Susan Collins, Jon Husted, and Dan Sullivan - joined an attempt by Democrats to ban Trump's "anti-weaponization" fund on Thursday in a measure that didn’t pass, along with two other Republican attempts to end the fund.

"This whole exercise is to pass President Trump's top agenda item to secure the border and fund ICE. What's happening on the floor right now shows the solidarity that we have with the president," Republican Senator Jim Banks, a Trump ally, said as lawmakers voted.

Trump's next big challenge is likely to be his expected nomination of his former attorney, Todd Blanche, as permanent U.S. attorney general, a move that could face an uphill battle in the Senate. The first stop would be the Senate Judiciary Committee, a panel that includes Trump retribution casualty Cornyn, who said his support would depend on how Blanche answers certain questions.

"The attorney general is not the president's private lawyer," Cornyn told reporters. "I want to make sure he understands the difference and is committed to making sure that the law is enforced."