US President Donald Trump’s self-inflicted wounds are making it harder for some US Republicans to remain quiet or unwaveringly loyal during what could be an inflection point in his presidency.

Fissures are emerging among disorientated Republican lawmakers as the president is threatened with impeachment, as is his troop withdrawal from Syria and his abortive push to host the Group of Seven (G7) at his golf resort.

Democrats are readying articles of impeachment, the catalyst being Trump’s July phone call to his Ukrainian counterpart in which he urged the European ally to investigate his political rivals.

No sitting Republican lawmaker has publicly expressed their intent to vote for Trump’s impeachment in the House of Representatives or Senate conviction if the process gets that far.

But some have inched closer to backing the process.

“I think we are getting to that point” where an increasing number of Republicans could support impeachment, retired GOP congressman Charlie Dent told CNN Monday, adding he has spoken with current lawmakers in his party who are “exasperated” by Trump.

Senator Lindsey Graham, one of Trump’s fiercest defenders in Congress, in recent days expressed openness to impeachment proceedings if new evidence of wrongdoing by Trump emerges.

“I mean . . . show me something that . . . is a crime,” Graham, who has lambasted Trump’s Syria withdrawal, told Axios in an interview, published on Sunday.

“If you could show me that, you know, Trump was engaging in a quid pro quo, outside the phone call, that would be very disturbing.”

Graham has since expressed optimism that Trump will reach a viable solution in Syria. But his criticisms resonate in a Congress where Republicans have feared defying the president or antagonising his base.

Trump stands accused of seeking to condition congressionally mandated military aid to Ukraine on the country mounting an investigation of Democratic presidential hopeful Joe Biden and his son Hunter, who did business in Ukraine.

For his part, the president remains confident that his party has his back.

“I think I have great Republican support,” he told reporters Monday.

Graham has said he sees no impeachable behaviour by Trump on the call with Ukraine.

But others have. John Kasich, a former congressman and Ohio governor, said Friday he has been pushed “across the Rubicon” and would vote to impeach if he were still in the House.

That followed a wild White House news conference by the chief of staff Mick Mulvaney who announced that Trump’s own Florida resort had been chosen for next year’s G7 summit, and acknowledged there was a quid pro quo on withholding aid to Ukraine.

Mulvaney walked back his quid pro quo comments amid an angry backlash, but his announcement of Trump National Doral as the G7 site infuriated several Republicans.

When Trump phoned in to a meeting between Mulvaney and moderate Republicans and learned they would not defend his decision, Trump scrapped the Doral plan, the New York Times reported.

With frustration building, congressman Francis Rooney on Friday became the first Republican to publicly say he is considering supporting the impeachment inquiry.

“I don’t think you can rule [impeachment] out until you know all the facts,” the Florida lawmaker told CNN.

Rooney also announced he will not seek reelection next year, perhaps allowing himself to speak more critically of Trump.

As for a prospective Senate trial that could remove the president, “I just want to get as much information as we can, make an assessment consistent with the law and the Constitution,” he said.

Conviction requires a two-thirds majority, meaning out of 53 Republicans in the 100-member Senate, at least 20 would need to vote against Trump.