New York, May 9

As the US edges to a constitutional crisis with the Democratic-controlled House of Representatives unleashing a multi-pronged attack on President Donald Trump and his officials and him launching a counter-offensive, both sides are working on the political calculus of impeachment.

"We are now in a constitutional crisis", the chair of the House Judiciary Committee, Jerry Nadler, declared on Wednesday as the standoff with Trump intensified.

If a full-blown constitutional crisis develops, the Democrats may impeach Trump - a move that a large section of the party base demands but the leadership is cautious about.

However, Trump himself may be trying to precipitate an impeachment if he sees electoral gains.

He told a rally of his supporters in Florida on Wednesday night: "They want to do investigations instead of investments. I think it drives us right on to victory in 2020."

He may think that an impeachment - or continuing investigations - that could drag on while the election campaigns get underway would rally his base and help him play the martyr while Democrats are mired in an electoral debate over him at the expense of policies.

Speaker Nancy Pelosi, who has said she is against impeachment, saw through this ploy. She said on Tuesday that because Trump wants to "solidify his base" regardless of the cost to the nation, he "is goading us to impeach him, that's what he's doing every single day. He's just taunting, taunting, taunting because he knows it would be divisive".

Pelosi may want her party to avoid the trap, but by Wednesday she was exasperated. "He's becoming self-impeachable" and making a case for it every day, she said at a Washington Post event.

Setting the stage for a constitutional crisis, House Judiciary Chairman Jerry Nadler's committee voted to hold Attorney General William Barr in contempt for refusing to give it the full report of the inquiry into the Russian interference in 2016 elections.

Trump retaliated by exercising his executive privilege to withhold it from the panel.

The full House is expected next week to follow-up the committee vote to hold him in contempt. Theoretically, the House may have the power to arrest Barr if it votes to declare him in contempt, although it is unlikely to go that far.

The House under Republican control in 2012 held former President Barack Obama's Attorney General Eric Holder in contempt for refusing to hand over information about a sting operation against the illicit gun trade that went awry. But it amounted to just a slap on the wrist.

Trump's exercise of his executive power against the release of the full inquiry report could precipitate a constitutional crisis because the House -- should it vote so -- would be holding Barr in contempt for complying with a presidential order.

On the other hand, the concept of executive privilege is itself controversial and Democrats, who are already questioning it, could ultimately take the matter to courts. It is not explicitly mentioned in the Constitution but has been exercised in the past as an extension of the powers of the president and the separation of the executive and legislative branches of government.

The inquiry into Russian meddling conducted by Special Counsel Robert Mueller found that neither Trump nor his campaign had colluded with Russians during the 2016 election, disappointing many Democrats who had expected the probe to confirm their claims and help unseat the President.

The version of the report that was released by Barr had portions blacked out as they related to testimony that is legally secret, ongoing investigations or innocent third parties.

But the Democrats clamour for it in entirety hoping to find leads for further investigations or to enable them to take up the charge of obstruction of justice against Trump -- an impeachable offence -- on which Mueller refused to neither clear Trump nor charge him with it.

Opening another front, House Intelligence Committee Chairman Adam Schiff issued a subpoena to the Justice Department demanding the unredacted version of the report.

Yet another House panel, the Way and Means Committee that deals with tax matters, is embroiled in a standoff after requesting the Treasury Department for Trump's recent tax records. Treasury Secretary Steven Muchin has refused to comply and the Committee chair Richard Neal has said he will decide on Thursday whether to go to court to compel him.

Unlike all recent presidents, Trump has refused to publish his tax returns saying they were under audit.

Democrats want to examine the tax records to see if there are any irregularities they can pursue.

The House Intelligence and Financial Services Committees have demanded Trump's tax records from two banks, but Trump has gone to court to try to block them from complying.

The New York Times has published information from his tax returns for the decade 1984 to 1995 that show he had run up losses totalling $1.17 billion and did not pay taxes for eight years.

Puncturing his image of being the master of the art of the deal, the Times said that "in multiple years, he appears to have lost more money than nearly any other individual taxpayer".

Trump, however, defended his record in tweets claiming it was "a sport" by real estate developers to show losses for taxes purposes by using tax shelters.

The Democratic Party-controlled New York state Senate voted on a workaround on Wednesday to make state tax returns that contain information in the federal tax forms available to some Congressional committees.

The House Judiciary Committee has also demanded documents from former Trump White House lawyer Don McGahn and asked him to testify before it. He has refused to give them the papers, paving the way for another confrontation.

Meanwhile, the Intelligence Committee of the Senate controlled by his own party has ordered Trump's son, Donald Jr., to appear before it. It is likely seeking information about his talks with Russians that is mentioned in the Mueller report.

As US edges to 'constitutional crisis', Trump, Democrats weigh impeachment impact