A funny thing happened on the way to the U.S. midterm elections. All the conventional wisdom about a first-term President and his party taking a beating in the Nov. 6 vote has been turned on its head because of Donald Trump’s uncanny ability to energize his base – and divide everyone else.

He did it again this week, even when the moment called for restraint as the spectre of political violence descended on the United States. Instead of being chastened by the news that pipe bombs had been sent to the Clintons, Obamas and other Democratic figures, Mr. Trump did not hesitate to make political hay of the incident, blaming “anger” in society on a hostile media.

This willingness to go lower than many of us thought possible in U.S. politics is Mr. Trump’s secret weapon. It’s why every time Democrats think they’ve got him cornered, they watch haplessly as he turns the tables to make them look like entitled troublemakers or just plain riff-raff.

The spectacle that was the U.S. Senate hearing into allegations of sexual misconduct against Supreme Court Justice Brett Kavanaugh was supposed to be a turning point, prompting women to turn out in record numbers to vote Democrat in November. Instead, it’s looking like a wash, as Mr. Trump attacks Justice Kavanaugh’s accuser to fire up his anti-elite base of white men. Several analysts who track individual congressional races, such as the well-regarded Cook Political Report, have lowered the ceiling on potential Democratic gains in the wake of the Kavanaugh affair.

Indeed, a Wall Street Journal/NBC News poll this week pegged Mr. Trump’s approval rating at 47 per cent, the highest level of his presidency, compared with a 49-per-cent disapproval rating. Over all, Mr. Trump’s average approval rating of 44 per cent matches that of former president Barack Obama just before the 2010 midterm elections. But unlike the “shellacking” (Mr. Obama’s words) that Democrats experienced that year – losing a postwar record 63 seats, and their majority, in the House of Representatives – Republicans are not facing decimation this year. The reason is Mr. Trump.

While Democrats are still favoured to win the House – they need a net gain of 23 seats to do so – unprecedented midterm enthusiasm among Trump supporters will prevent a GOP bloodbath. If the trend seen during the past two weeks continues, Republicans could even hold on to the House.

Democratic dreams of taking the upper house of the U.S. Congress have been all but shattered by the party’s leftward lurch. Democrats had already written off holding their Senate seat in North Dakota, a state Mr. Trump carried by more than 35 percentage points in the 2016 presidential election. But moderate Democratic incumbents in Indiana and Missouri, considered safe not long ago, are now also fighting for survival and forced to distance themselves from their party.

First elected in the 2006 Democratic wave, Missouri Senator Claire McCaskill, who has a track record as a moderate, nevertheless had to remind voters in a radio ad this week that she is “not one of those crazy Democrats.” Indiana Democratic Senator Joe Donnelly put out an ad that shows him declaring, while chopping wood: “I split with my own party to support funding for Trump’s border wall.”

The ads spoke volumes about how worried party strategists have become as more radical left-wing Democratic candidates in urban strongholds or solidly blue states steal the limelight. Senators Elizabeth Warren of Massachusetts, California’s Kamala Harris and Kirsten Gillibrand of New York State are megastars among the Democratic base and contenders for their party’s presidential nomination in 2020. But among independent voters, who usually decide national elections, they are seen as extreme or dangerous ideologues.

Therein lies the Democratic dilemma. Having for the most part lost the white working class, the party now almost exclusively targets voters who see themselves as belonging to marginalized groups that are oppressed by dominant capitalist, sexist and racist structures in society.

But to win at identity politics, you need to be better at it than your opponent. And no current American politician is better at practising identity politics than Mr. Trump. To be sure, the President targets a different audience than the Democrats. But he connects with his voters far more effectively and viscerally than Ms. Warren, Ms. Harris or Ms. Gillibrand do with theirs.

“Radical Democrats want to turn back the clock [and] restore the rule of corrupt, power-hungry globalists,” Mr. Trump told a rally this week in Texas. “A globalist is a person that wants the globe to do well, frankly, not caring about our country so much.”

With that, Mr. Trump embraced the “nationalist” label that others have used disparagingly against him. It’s why Democrats may not have much to celebrate even if they take the House.