WASHINGTON — President Donald Trump and Congress wheeled closer to a constitutional crisis Tuesday, as Democrats continued to struggle with what many view as competing impulses to impeach the president and to follow a more politically cautious path.

In the morning, the White House instructed former counsel Don McGahn to ignore a subpoena for documents related to special counsel Robert Mueller's investigation into the Trump operation's ties to Russia and possible obstruction of justice.

In the afternoon, Judiciary Committee Democrats in the House were moving a step closer to a vote Wednesday by the full chamber on whether to hold Attorney General William Barr in contempt of Congress for failing to turn over Mueller's report and related documents — even though panel staff and Justice officials had met earlier in the day to try to avert the vote.

For now, both sides are circling each other, with Democrats having developed no clear strategic tack beyond trying to get more information about Trump into the public realm.

Rudy Giuliani, Trump's personal lawyer, said in an interview with NBC News that Democrats are pursuing "a political investigation" with no merit and that the president is smart not to give in.

"I don’t think they expected that he was going to fight back as hard as he has. But he has every right to," said Giuliani, who does not represent the president on matters related to White House documents and personnel. "If I represented him, I wouldn’t give them a damn thing that they didn’t earn. I’d want a court to say that’s a legitimate investigation."

Part of the problem for Speaker Nancy Pelosi, D-Calif., and her fellow House Democrats is that their caucus remains torn between two twin-pronged arguments on impeachment.

On the "pro" side, many Democrats view past acts by the president as impeachable and some see his current defiance of congressional oversight as rising toward that bar. On the "anti" side, a large number of Democrats are swayed by the case that any attempt to remove the president would fail in the Senate and the fear that a House vote to impeach him would be politically fatal for their own party.

Nonetheless, the anti-impeachment faction can see the argument that the president's behavior is inconsistent with the faithful execution of the duties of his office, and the pro-impeachment lawmakers are aware of the political risks of their preferred course.

Democrats and Republicans often point to the 1998 elections, when Democrats bucked midterm trends by picking up a net of five House seats while Republicans were moving toward the impeachment of President Bill Clinton, as evidence that a failed effort to remove a president can create a political backlash.

But the House didn't impeach Clinton until after that year's election, and the Senate trial didn't end until the following year. In the next presidential election, Republican George W. Bush won the White House narrowly, with Democrats netting one House seat.

For now, the question of impeachment can be put off as the Democratic House battles Trump over documents and witnesses that some of his adversaries hope would contain the seeds of action against him. But pressure is building in the Democratic ranks outside the House.

Sen. Elizabeth Warren, D-Mass., who is seeking the party's nomination, reiterated her call to start the process immediately in a Senate floor speech Tuesday.

"This is not about politics, this is about the Constitution of the United States of America," she said. "We took an oath not to try to protect Donald Trump, we took an oath to protect ... and serve the Constitution of the United States of America, and the way we do that is we begin impeachment proceedings now against this president."

And former Vice President Joe Biden, who is leading the 2020 primary field in the polls, has said that Congress has "no alternative" but to pursue impeachment if Trump continues to block its efforts to follow up on the Mueller probe.

Pelosi's own commentary Tuesday pointed to the Democratic dilemma.

"Trump is goading us to impeach him," she said at an event sponsored by Cornell University's political institute. "He knows that it would be very divisive in the country, but he doesn’t really care. He just wants to solidify his base.”

But after Senate Majority Leader Mitch McConnell, R-Ky., took to the Senate floor Tuesday to declare the "case closed" in the Mueller investigation, Pelosi and Senate Minority Leader Chuck Schumer, D-N.Y., issued a joint statement bashing McConnell, Barr and Trump in terms that tugged at the grounds for impeachment.

"On every issue that matters in people’s lives, the administration and a complicit Republican Senate are waging an unprecedented, unwarranted, unconstitutional and utterly dangerous campaign of stonewalling," they said. "Senator McConnell continues to brag about being the ‘grim reaper,’ sending bipartisan House legislation to a Senate legislative graveyard, as the administration refuses to respect Congress’s constitutional oversight role and provide Congress and the American people with the truth."

Stacey Plaskett, a former Justice Department lawyer and a Democrat who represents the Virgin Islands in the House, said her party is moving forward with the investigations without a set course on the impeachment question because there's no agreement on that.

"I don’t think that there is a strategy," she said. "I think we have a fractured party in terms of what we each believe we should be working on."

House Judiciary Committee Chairman Jerry Nadler, D-N.Y., appears to favor impeachment, she said, because "he's probably informed by his own legal background, the committee that he chairs and his own constituents — and [the belief] that he has a constitutional duty to investigate and move toward that, whereas there are other members that believe that unless we have the will of the American people that we're going after fool's gold."

It's not clear at this point that Pelosi would have the votes on the House floor to impeach Trump — even if she wanted to — and holding a vote would put members of her caucus in swing districts in a perilous position between their liberal supporters and the cross-over voters who helped elect them.

"Especially for moderates, there’s a deep concern about appearing overly zealous, overly political or thirsty for impeachment," said a senior aide to a moderate Democrat who asked to remain anonymous because he was not authorized to speak on the record. "I think the speaker has done a great job in taking that off the table publicly and saying you can investigate."

Giuliani said that he thinks Pelosi is trying to temper her caucus.

"With her remarks today, she’s trying to encourage them to back off," Giuliani said in an interview with NBC News. "I do think that a lot of them, whether they’re right or wrong, still use the Clinton thing and say if we go forward and we don’t have broad support, it’s going to turn on us."