Trump has certainly put the Democrats in a difficult position. His past actions to disrupt and interfere with the investigation of special counsel Robert Mueller are spelled out in detail in Mueller's report. House Speaker Nancy Pelosi is facing growing pressure to commence impeachment proceedings. Credit:AP Attorney-General William Barr has said the evidence does not constitute obstruction of justice. Others strongly disagree, including many House Democrats who want to hear more about those episodes. Beyond the contents of the Mueller report and what they say about the question of obstruction, the administration has further inflamed things by blocking virtually all requests from congressional committees for documents for investigations into various Trump-related matters. The President also ordered former White House counsel Donald McGahn not to testify before the House Judiciary Committee. When McGahn defied a subpoena from the committee, chairman Jerrold Nadler threatened to hold a vote to hold him in contempt.

Loading The administration's resistance has put before Pelosi and other House leaders the question of whether an administration can indefinitely stonewall the legislative branch with impunity, a question with constitutional and practical significance for this and future presidencies. The time for an answer might still be premature, given current legal proceedings. But as Democrat Senator Elizabeth Warren put it during a CNN town hall last month, "There is no political inconvenience exception to the United States Constitution". The politics of impeachment remain fraught. Many Democrats still believe the party should focus all its energies on the 2020 election and seek to deny the President a second term through the ballot box. That's a far cleaner remedy than the high stakes of an impeachment proceeding that would die in the Senate if it reached fruition in the House. But for Democrats, there is no guarantee of victory in the 2020 election. For all his vulnerabilities, Trump presides over a strong economy and enjoys the power of incumbency, which he is prepared to use to the fullest.

Few Democrats are unduly optimistic about victory in 2020, despite the party's strong performance in the 2018 midterm elections and signs of continued energy by the same kinds of voters who helped deliver that election outcome. The Democrats remain scarred by what happened in 2016. Loading Pelosi knows that public opinion overall is not on the side of the Democrats. A majority of Americans continue to oppose impeachment. But public opinion among Democrats is in a different place. That's why a number of candidates for the Democratic nomination have expressed their support for at least the opening of an inquiry. It's a popular position with the base. Pelosi can play both sides only for so long. At some point, she and her committee chairs will have to make a decision. That may not be for months, given the legal machinery now clanking along. She will try to keep deferring an ultimate decision, but the consequences of acting or not acting become more pressing as time passes. Pelosi and Trump continue to circle one another with taunts and insults. Pelosi criticised Trump for abruptly walking out of a meeting with congressional leaders on infrastructure on Wednesday at the Oval Office, after she had accused him of a coverup during a meeting with her own troops.

Pelosi on Thursday said the President could benefit from a "leave of absence" and perhaps needs "an intervention, for the good of the country" by family or staff. Trump responded on Thursday by polling his staff at a news conference, asking them to explain to reporters that he wasn't angry or intemperate when he walked out of the meeting with Pelosi and other congressional leaders. It was an extraordinary display on the part of a President. During a meeting to support American farmers, President Donald Trump asked counsellor Kellyanne Conway how his conduct was in a meeting with Pelosi. Credit:AP Trump called himself a "stable genius". He said the Speaker is a "different person" than the leader he began dealing with earlier. He called her "crazy Nancy". He said, "She's lost it." Such is the state of the relationship between the President and the most powerful Democrat in the country.

Pelosi bested Trump earlier in the year during the government shutdown when she called his bluff and forced him to reopen agencies without giving him funding for his border wall. He responded later by declaring a national emergency to allow him to take the money from other funds in the Defence Department. In this latest standoff, each has pushed the other into a corner. Pelosi certainly knows how to provoke the President, as she demonstrated again the past few days. But his defiance of Congress has left her with the most difficult of choices, for the country and for her party. Loading Trump is pushing the country toward a constitutional crisis - many believe it is already here. His actions have riled the Democrats on Capitol Hill and generated anger in the party's base. Pelosi is now buffeted as she weighs what to do. Sliding into impeachment is hardly the preferred choice, but can she resist the political forces inside her party that are pushing in that direction? The Speaker plays a long game. As Trump has learned, she is shrewd, tough and experienced. Still, the coming test over impeachment could be the most difficult of her career.