Chris Christie, the governor of the US state of New Jersey, has launched his bid to become president, telling supporters he is ready to begin what he called a noble effort to "lead our country and to change the world".
With his declaration, Christie, 52, becomes the 14th Republican to enter the race for the party's nomination for 2016, with no clear frontrunner so far.
"America is tired of hand-wringing and indecisiveness and weakness in the Oval Office," Christie, the Republican governor of a largely Democratic state, declared on Tuesday.
"If we're going to lead, we have to stop worrying about being loved and start caring about being respected again, both at home and around the world," he said in a veiled criticism of President Barack Obama, a Democrat.
Christie was scheduled to head to the early-voting state of New Hampshire later on Tuesday.
Both the Republican and Democratic parties will select their nominees during the primaries, starting on January 2016. The eventual winners will then face off in a general election on November 2016.
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Christie has slipped from favour with fellow party members and faces a tough sell with many conservatives in a crowded election field.
He once was one of the nation's most popular state leaders, and his turn as head of the Republican Governors Association was widely viewed as a success in the 2014 midterm elections.
Christie had a landslide re-election to a second term as governor in 2013, but he was later nearly felled by scandal involving his aides, and deliberate traffic jams at a bridge to New York City in an effort to hurt a political rival.
Following the controversy, his approval ratings have reached record lows at home.
Aides now try to emphasise what they describe as his charismatic personality, quick wit and plain-spoken manner, while fighting some critics' view of him as a bully.
In Tuesday's speech, Christie said both the nation's main political parties "have failed our country" and called for more compromise in politics.
Christie often emphasises his working-class roots as a contrast to candidates like Jeb Bush, the son and brother of presidents.
He used his announcement in the gymnasium of his old high school to show how his upbringing shaped him in articulating his vision for the country.
But his antagonistic style - critics call him an obnoxious bully - has been on display since he became governor in 2010, with videos posted on YouTube that showed him telling people to "shut up" or calling constituents "numbnuts."
Source: Al Jazeera and agencies