Donald Trump has confronted one of the most perilous moments of his presidency after a former lawyer pleaded guilty to campaign financing charges and a former election chief was convicted of fraud.

Although the US president largely ignored the jarring back-to-back blows at a campaign rally in West Virginia, questions mounted about his possible legal exposure and political future.

Mr Trump’s former campaign chairman, Paul Manafort, was convicted of financial crimes at nearly the same moment Mr Trump’s former personal lawyer, Michael Cohen, pleaded guilty to a series of charges on Tuesday.

The crimes include campaign finance violations that the lawyer said he carried out in coordination with Mr Trump.

With two men who played prominent roles on the president’s campaign convicted of multiple criminal charges, the investigations circled ever closer to Mr Trump.

However the president spent more than an hour at a rally in Charleston painting a rosy view of his accomplishments in office, ticking off developments on trade, taxes, North Korea and even his plans for a space force.

“What we’re doing is winning,” Mr Trump told cheering supporters.

“Where is the collusion?” he demanded, underscoring that Manafort’s crimes had occurred before he became involved with his 2016 campaign.

“You know they’re still looking for collusion,” the president said.

Mr Trump did say he felt “badly for both” men, but he largely ignored Cohen’s guilty pleas to eight felonies.

Manafort was convicted on Tuesday in Virginia on charges brought by special counsel Robert Mueller, who is investigating Russian interference in the 2016 election and potential obstruction of justice.

Cohen pleaded guilty in New York, saying he and Mr Trump had arranged the payment of hush money to porn star Stormy Daniels and a former Playboy model to influence the election.

It is the Cohen case that places Mr Trump in the most jeopardy, legal experts said, as the longtime personal “fixer” acknowledged his role in a scheme to pay off women who accused the future president of sexual misconduct.

“It’s going to be hard for the president to try to discredit all this. It’s circling him,” said David Weinstein, a former federal prosecutor who is not involved in the case.

The crowd in West Virginia loudly chanted “drain the swamp!” and “lock her up!” – in reference to old rival Hillary Clinton – despite the fresh corruption convictions and looming prison sentences for his former advisers.

Trump Lawyer Investigation
Michael Cohen pleaded guilty to a series of charges at a court in New York AP/Craig Ruttle)

Manafort’s conviction served as a vindication of Mr Mueller’s work as investigators continue to probe potential misdeeds by the president and those in his orbit.

Mr Mueller’s team also had referred evidence in the Cohen case to federal prosecutors in New York.

Mr Trump’s current attorney, Rudy Giuliani, sought to cast the blame solely on Cohen in a statement, saying: “There is no allegation of any wrongdoing against the President in the government’s charges against Mr Cohen.”

Mr Trump’s legal team has also been engaged in negotiation with Mueller’s team for months about a potential sit-down with the president, but has objected to the scope of the questions.

In a separate courtroom on Tuesday, prosecutors and defence attorneys for Mr Trump’s former national security adviser Michael Flynn agreed to postpone his sentencing after he pleaded guilty to lying to the FBI about his contacts with a Russian official.

It was a sign his cooperation was still needed in Mr Mueller’s probe.

Mr Trump’s allies reasserted late on Tuesday that it is the White House position that a president cannot be indicted, referring to a 2000 opinion of the Justice Department’s Office of Legal Counsel, which provides legal advice and guidance to executive branch agencies.

The president’s lawyers have said Mr Mueller plans to adhere to that guidance, though Mr Mueller’s office has never independently confirmed that.

There would presumably be no bar against charging a president after he or she departs the White House.

Michael Avenatti, a lawyer pressing a civil case against Mr Trump for Ms Daniels, who has said she had sex with the president, tweeted on Tuesday that the resolution of the criminal case against Cohen “should also permit us to proceed with an expedited deposition of Trump under oath about what he knew, when he knew it, and what he did about it”.

The Supreme Court in 1997, ruling in a sexual harassment lawsuit brought by Paula Jones, held that a sitting president could be made to answer questions as part of a lawsuit.

That ruling did not directly address whether a president could be summonsed to give evidence in a criminal investigation.