Former New Jersey governor Chris Christie on Tuesday launched his 2024 US presidential campaign with a withering attack on the Republican front-runner, Donald Trump, calling him a "self-serving mirror hog" and faulting other rivals for avoiding direct confrontation.

Christie, 60, was an adviser to Trump's successful 2016 White House campaign but has since become a vocal critic over the former president's false claims that the 2020 election was rigged.

A former federal prosecutor, Christie presented himself as the lone Republican contender willing to go toe-to-toe with the bellicose Trump.

"A lonely, self-consumed, self-serving mirror hog is not a leader," he said.

At one point, he delivered a mocking impression of Trump claiming he would build a southern border wall at Mexico's expense and said Trump, more than Biden, was to blame for the country's failed immigration policy.

In a post on his social media site, Trump made a reference to Christie's weight and called him a "failed governor."

Christie has not fared well in public opinion polling thus far. He netted just 1 percent support from potential Republican primary voters in a Reuters/Ipsos poll in May, compared with Trump's 49 percent support and Florida Governor Ron DeSantis' 19 percent support.

Other Republicans seeking the party's nomination to challenge President Joe Biden include former UN Ambassador Nikki Haley and US Senator Tim Scott. Trump's former vice president, Mike Pence, is set to enter the race on Wednesday.

Taking the stage to the sounds of Bruce Springsteen, Christie accused both Trump and Biden of "making us smaller" by dividing Americans. He called Biden a "nice guy" but said he was out of his depth, in a reference to the 80-year-old's age. (Reuters)