During a speech starting his 2024 campaign, former US Vice President Mike Pence delivered his most powerful rebuke of Donald Trump to date.

The Republican charged Mr. Trump with betraying the US constitution and abandoning conservative beliefs.

On Wednesday, the former Indiana governor and congressman officially launched his presidential candidacy.

The decision places him against his two-time running mate, under whom he served in the White House from 2017 to 21.

Mr Pence stated in a speech in Ankeny, Iowa, that Mr Trump had encouraged the mob that invaded the US Capitol on January 6, 2021, and that Mr Trump had falsely asserted that Mr Pence had the capacity to overturn the election result.

“But the American people deserve to know that on that day, President Trump also demanded that I choose between him and the constitution,” he explained.

“Voters will now face the same choice: I chose the constitution and will always do so.”

He also stated that Mr. Trump’s actions on January 6 should disqualify him from re-election.

“Anyone who puts themselves above the constitution should never be president of the United States,” he declared.

“And anyone who asked someone else to put them over the constitution should never be elected President of the United States again.”

Mr. Pence, 64, also attacked Democratic Vice President Joe Biden, claiming that neither he nor Mr. Trump are like ordinary Americans who know how to “treat each other with kindness and respect even when we disagree.”

Much of his address centered on his concerns with Mr. Trump, but he also attacked another Republican 2024 opponent, Florida Governor Ron DeSantis.

“Donald Trump and others who would seek the presidency would walk away from our traditional role on the world stage,” he said, referring to Mr. DeSantis’ recent remarks about the Ukraine conflict.

In a later CNN town hall, he continued to criticize his opponents, calling Mr Trump a “genius” for previously calling Russian President Vladimir Putin a “genius.”

“I can tell the difference between a genius and a war criminal, and I know who needs to win in Ukraine,” he remarked.

He did, however, criticize prosecutors for looking into Mr. Trump’s alleged misuse of secret data after leaving office, saying that “indicting a former president in the United States sends a terrible message to the world.”

It comes after prosecutors absolved Mr. Pence of misconduct in his handling of classified information last week.

Mr. Pence was one of eight Republican presidential hopefuls who attended the Roast and Ride fundraiser at the Iowa State Fairgrounds last weekend.

He arrived on a Harley Davidson, along with several hundred other motorcyclists who went in convoy to raise money for war veterans. But that wasn’t enough to get people excited about his campaign.

The most enthusiastic answer went to Ron DeSantis, who promised to “fight the woke” wherever he finds it.

Mr Pence’s speech, by contrast, was flat and lackluster, underscoring why a former vice president with a national name is trailing badly in surveys.

According to a Reuters-Ipsos poll issued last month, Mr Pence is polling at 5%, while Mr Trump is polling at 44%.

Todd Wilson, a former Trump supporter, believes Mr Pence “needs to be a little bit stronger.”

“I think if you’re going to be president, you got to have a little bit of a bulldog in you,” he added of the candidate’s humility. So I’m hoping for that from Pence.”

The Republican candidacy for the 2024 presidential nomination is becoming increasingly crowded.

Former New Jersey Governor Chris Christie announced his candidacy on Tuesday. North Dakota Governor Doug Burgum declared his candidacy on Wednesday as well.