WASHINGTON (Reuters) - President Donald Trump survived one of the biggest threats to his presidency when Thursday's hugely awaited congressional testimony by the FBI chief he fired did not yield any explosive new disclosures about his campaign's alleged ties with Russia.

But former FBI Director James Comey's remarks to a packed hearing of the Senate Intelligence Committee left the Republican president far from unscathed.

Comey recounted in vivid detail conversations with Trump that he viewed as an effort to undermine an investigation of possible collusion between the Trump campaign and Russia.

He also said Trump's comments after firing him on May 9 that the FBI was in disarray and that its members had lost confidence in Comey "were lies, plain and simple."

Still, Comey handed Trump and his supporters some fresh ammunition when he confirmed he had told the president the investigation was not focused on him personally.

Even Senator Marco Rubio, who was among a number of Republicans who battled Trump for the 2016 Republican presidential nomination, seemed to be advocating for him at times during the hearing.

Rubio asked Comey why he did not directly tell Trump that he thought the president was making inappropriate requests of him.

Comey replied that he did not know. “I was a bit stunned, and didn’t have the presence of mind,” he said.

A Republican close to Trump said the president felt very good about Comey's testimony, particularly since it bore out his earlier statement that the former FBI director had told him he was not under investigation.

But the cloud from the Russia probe still hangs heavily over Trump's White House.

Comey's firing set the stage for the appointment of a special counsel, Robert Mueller, who has taken over the investigation. Congressional probes, including one by the Senate intelligence panel, are ongoing.

Russia has denied interference in last year's presidential campaign. The White House has denied any collusion with Moscow.

But Senator Dianne Feinstein, a Democrat who sits on the intelligence committee, said the matter was nowhere near over.

"It’s a big investigation, and these are facts. ... You have to dig for, and do a lot of analysis."

Several Democrats said Trump's conversations with Comey seemed to build a case of obstruction of justice.

“The lawyers are going to dig into obstruction of justice,” Senator Ron Wyden, a Democrat on the intelligence panel, said after the hearing. "I believe the evidence just keeps piling up that there has been a very real presidential abuse of power.”

But Paul Ryan, the Republican speaker of the House of Representatives, said Trump's interactions with Comey may have reflected his lack of political experience rather than an effort to pressure the FBI director.

Ryan said Trump may not have been "steeped" enough in the FBI's independence from the White House.

"He's new in government, and so therefore I think he's learning as he goes," he told reporters. "I'm not saying it's an acceptable excuse. It's just my observation."

A LONG SUMMER

Trump could face even more problems over the coming months if the stream of details leaking out about the Russia investigation continues to grab the spotlight at a time when the White House wants to focus on priorities such as rolling back the Obamacare healthcare law and overhauling the tax code.

"It distracts the administration and gives Republicans in the House and the Senate, many of whom have not been Trump supporters from the beginning, a reason to keep their distance and not get behind him," said Andy Smith, director of the University of New Hampshire Survey Center, which conducts political polling.

"It’s going to be a long summer,” Smith said.

Trump's core supporters are hunkering down for a fight.

Great America Alliance, one pro-Trump group, spent $400,000 this week running ads attacking Comey, said Eric Beach, who runs the group.

The ad lambasted Comey as “just another D.C. insider" and included images of militant attacks abroad to suggest Comey had not been focused enough on protecting Americans.

But the investigation has contributed to a steady erosion of Trump's political capital. According to a Reuters/Ipsos opinion poll taken from June 1 to 5, even before the Comey testimony - 38 percent of Americans said they approved of Trump, versus 58 percent who disapproved.

"I think the situation is getting much more serious for Mr. Trump,” said Jon Bond, a political science professor at Texas A&M University. “The Mueller investigation is going on. I suspect that information that came out in today’s hearings is going to feed into that investigation. It looks like to me that the president is in increasing jeopardy.”

(Additional reporting by Susan Cornwell, Richard Cowan, Steve Holland, Ginger Gibson, Patricia Zengerle and Eric Beech; Editing by Peter Cooney)