Democratic Party talk of impeachment intensified Tuesday after Donald Trump's former lawyer Don McGahn refused to testify about obstruction allegations against the US president.

House Democratic leaders held off fresh pressure from rank-and-file legislators to launch an effort to remove the president, after the White House again stymied their probe into Trump's actions in the alleged Russia meddling investigation.

But McGahn's refusal to abide by a subpoena from the House Judiciary Committee stoked the furor among Democrats, with more demanding the party resolve to put the president on trial.

"Stonewalling Congress on witnesses and the Mueller report only enhances the President's appearance of guilt, and as a result, he has pushed Congress to a point where we must start an impeachment inquiry," said Representative Mark Pocan. "We need to do our job & vote on impeachment," tweeted Representative Alexandria Ocasio-Cortez.

House Speaker Nancy Pelosi, who has so far fended off pressure to pursue that option, scheduled a party meeting Wednesday to discuss the issue.

"I don't think we're there at this point in time," House Majority Leader Steny Hoyer, Pelosi's deputy, said Tuesday.

Hoyer said they would continue on the current path of investigating Trump, which has included seeking testimony and documents that so far the Trump administration has refused to hand over.

"And if it leads to a conclusion that we need to proceed further through other avenues, including impeachment, so be it," he said.

McGahn's refusal to appear before the Judiciary Committee was the most recent in a growing list of ways the White House has frustrated investigations by the Democrat-controlled House.

Trump's Justice Department has refused to turn over to Congress the unexpurgated version of Special Counsel Robert Mueller's final report on his Russia meddling and obstruction investigation, along with supporting documentary evidence.