President Donald Trump has taken aim at all his familiar political targets, plus adding a few fresh ones, during a campaign-style rally with “with my favourite deplorables.”

As November’s midterm congressional elections draw closer, Mr Trump has been increasingly strident in urging voters to support Republicans as a way of advancing his agenda.

And he left the overwhelmingly white and working-class audience at the Saturday night rally in Washington Township, Michigan, in no doubt that he is unlikely to start respecting the rules of conventional politics.

In addition to slamming a veteran female political leader, he ridiculed the press and slurred a leading Democratic critic by hinting that he had details of unnamed and unknown “scandals” that he said would ruin the politician’s political career.

That politician, Democratic Senator Jon Tester of Montana, drew the presidential ire for opposing the nomination of Trump’s White House doctor, Ronny Jackson, to run the Department of Veterans Affairs.

That nomination failed amid allegations of drunkenness and inappropriate behaviour which an official investigation failed to confirm.

“I know things about Tester that I could say, too,” Trump said without elaborating.

“If I said ’em, he’d never be elected again.”

Trump supporters were met by protesters demanding an end to the harassment of migrants. Photo: YouTube/MLive

However it was Michigan Senator Debbie Stabenow who attracted the bulk of his barbs.

An ardent supporter of abortion rights and gender equity, Stabenow has been an unrelenting critic of the Trump administration on almost every issue.

“You people just keep putting her back again and again and again,” he told the capacity crowd.

“It’s your fault,” he continued, citing Ms Stabenow as an obstacle to the appointment of conservative judges, building a wall on the US-Mexico border, ending “sanctuary cities” and protecting tax cuts approved by the Republican-led Congress.

In between slamming his enemies, Mr Trump also found time to take credit for the warming relations between North and South Korea, telling his audience “we’ll see how it goes.”

Turning to domestic matters, he threatened to shut down the US Government in September if his bid to build a wall on the Mexican border is denied funding by Congress.

“We come up again on September 28th and if we don’t get border security we will have no choice, we will close down the country because we need border security,” he said to cheers.

Trump made a similar threat in March to push for changes in immigration law that he says would prevent criminals from entering the country. The government briefly shut down in January over immigration.

A $US1.3 trillion spending bill, which Trump signed last month, will keep the government funded through the end of September. A government shutdown ahead of the November mid-elections is unlikely to be supported by his fellow Republicans who are keen to keep control of the US Congress.

Trump chose a friendly venue for his rally, which not coincidentally came the same night as the annual White House Correspondents’ Dinner, which he also skipped last year.

Ahead of the rally, Mr Trump said in a fundraising pitch he would rather be in Washington Township “with my favourite deplorables” than stuck in a Washington function room “with a bunch of fake news liberals who hate me.”

“You know, you may have heard I was invited to another event tonight, the White House Correspondents’ Dinner,” he told the crowd.

“But I’d much rather be in Washington, Michigan than in Washington, DC right now. That I can tell you.”

He also reportedly compared the size of the crowd at the rally to that he imagined to be at the White House correspondents’ dinner.

“By the way, you wanna see a lot of people? Go outside. We could have filled this place up probably five or six times,” he said, according to The Washington Post.

– with AAP