US PRESIDENT Donald Trump has praised a Montana congressman for body slamming a reporter — and said the assault helped him win a seat in the US House.

Speaking to a Missoula event, the New York Post reports that Mr Trump showered Republican Greg Gianforte with praise and recalled the candidate assaulting Guardian reporter Ben Jacobs last year for trying to ask a question.

“Any guy that can do a body slam, he’s my kind of guy,” Mr Trump said to applause. “I shouldn’t say that — (but) there’s nothing to be embarrassed about.”

Mr Trump said he initially thought Mr Gianforte’s act of violence would hurt his election chances, but “then I said ‘well, wait a minute, I know Montana pretty well, I think it might help him.’ And it did!” Mr Trump said. “He’s a great guy. Tough cookie.”

Mr Gianforte — who represents the state’s single at-large district — pleaded guilty in court last year to a charge of misdemeanour assault and is seeking re-election in November.

For his part, Mr Gianforte took the stage to cheers. “Mr. President, thank you for giving us hope again,” he said.

Mr Trump’s event kicked off a five-rally streak over seven days as the president tries to get Republican voters motivated for the November 6 elections.

Mr Trump told the crowd that immigration and border security will drive the midterm elections and suggested Democrats are supporting a “caravan” of Central American migrants travelling toward the border.

“This will be an election of (Justice Brett) Kavanaugh, the caravan, law and order and common sense,” Mr Trump said.

The Guardian later put out a statement blasting Mr Trump for making light of the incident.

“To celebrate an attack on a journalist who was simply doing his job is an attack on the First Amendment by someone who has taken an oath to defend it,” Guardian US editor John Mulholland said in a statement, in which he brought up the apparent slaying of a Washington Post writer at the Saudi Arabian consulate building in Turkey.

“In the aftermath of the murder of Jamal Khashoggi, it runs the risk of inviting other assaults on journalists both here and across the world where they often face far greater threats.”

Mr Trump has been criticised for his weak response to the reported death of Khashoggi, with many claiming his close ties to the Saudi royal family is the reason for his inaction.