NEW YORK: New Jersey Governor Chris Christie on Wednesday ended his bid for the United States (US) presidency, further whittling down a once-crowded Republican field led by billionaire real estate tycoon Donald Trump.

"I leave the race without an ounce of regret," Christie said in a Facebook post, one day after finishing sixth in the New Hampshire primary with only 7.4 per cent of the vote. In the Iowa caucuses last week, he finished in 10th place.

With such bleak results, it was unlikely that Christie would have been invited to participate in the next Republican debate on Saturday. And his campaign funds were drying up ─ a situation that often sounds the death knell for a presidential run.

"While running for president, I tried to reinforce what I have always believed ─ that speaking your mind matters, that experience matters, that competence matters and that it will always matter in leading our nation," Christie said. "That message was heard by and stood for by a lot of people, but just not enough and that's ok."

The 53-year-old Christie, a father of four, has a larger-than-life personality that endeared him to voters, especially when he fiercely stood up for residents affected by Hurricane Sandy, which caused unprecedented damage in New Jersey in 2012.

He scored perhaps his most triumphant moment on the campaign trail last weekend, when he skewered Republican rival Marco Rubio during a debate for robotically repeating his talking points.

But Christie bet big on New Hampshire and it did not pay off. He went to the Granite State more than 30 times, and held more than 150 events with voters.

The former federal prosecutor is a moderate Republican running a largely Democratic state who was once seen as one of the party's best hopes in 2016.

His image suffered in late 2013 after revelations emerged that senior aides ordered the closure of some lanes of the George Washington Bridge, a vital conduit between New York and New Jersey.

"Bridgegate" was interpreted by some as a reprisal against a local mayor who declined to endorse Christie for re-election.

His departure leaves six Republicans in the race: Trump, Rubio, Senator Ted Cruz of Texas, former Florida governor Jeb Bush, retired neurosurgeon Ben Carson and Ohio Governor John Kasich.