When Donald Trump made a remarkably statesmanlike first speech to both houses of Congress last Tuesday, some commentators argued that it showed his critics were wrong and he could be a more pragmatic, mainstream and effective President than they imagined. There were even hopes that his attempt to bring a divided nation together might herald a less confrontational style – and less government by Twitter in the middle of the night. Alas, such hopes were premature.

Mr Trump, who suggested he would stop picking “trivial fights”, has now started a huge one with his explosive claim that his predecessor, Barack Obama, authorised the tapping of his phone at Trump Tower during the presidential election campaign. Mr Trump added his usual gift to the headline writers by comparing Mr Obama’s alleged actions to the Watergate scandal that destroyed President Richard Nixon, even accusing Mr Obama of a witch-hunt worthy of “McCarthyism”. (This label was rather ironic, since Roy Cohn, Mr Trump’s early attorney and mentor, was Joseph McCarthy’s chief counsel during his investigations into communist activity in the US.)

Characteristically, the President provided no evidence to back up his remarkable allegations. Fake news, perhaps? Or maybe just alternative facts, as his aides call them. It appears that Mr Trump seized on claims by the right-wing Breitbart News website. Last year there were reports that the FBI was monitoring contacts between the Trump Organisation and Russian banks.

All roads in Washington today lead to Moscow, and Mr Trump’s latest tweets look like a naked attempt to divert attention from the crisis engulfing him over his team’s contacts with Russia, which have already forced the resignation of Michael Flynn as his national security adviser and put his Attorney General Jeff Sessions under pressure. It suits Team Trump to suggest that Mr Obama’s allies are behind the leaks.

The affair is another reminder of the stark contrast between Mr Obama – who insists he never authorised the surveillance of any US citizen or interfered in a Justice Department investigation – and Mr Trump. Mr Obama might not have fulfilled all the hopes and dreams invested in him when he became America’s first black president, but history will look back on some real achievements and will likely judge him a highly honourable man who gave his all for his country. Mr Obama would surely have beaten Mr Trump if the US Constitution had allowed him to run for a third term – when the contrast between them would have been even more evident. It is hard to imagine Mr Obama sinking to the depths of ordering the tapping of Mr Trump’s phone to help the Democrats keep him out of office. Indeed, it is the Democrats who were the most likely victims of such dirty tricks during the election campaign.

True, Mr Obama had good reason for wishing his successor ill. After all, Mr Trump wrongly claimed that Mr Obama was not born in the US and branded him “the founder of Isis”. Yet the dignified way in which Mr Obama handled his exit from the White House and the transition to the next administration indicated that the real President Obama was professional to the end, a man who would not sink to the desperate and illegal tactics of Richard Nixon. Michelle Obama’s “When they go low, we go high” speech would be pertinent to remember.