Tom Perez was seen as the establishment-backed candidate and will have to unite a divided party.
US Democrats have elected former Labour Secretary Tom Perez as their new national chairman.
Mr Perez, who served in the Obama administration, won the second round of voting at the Democratic National Committee meeting in Atlanta after a tightly-fought contest.
He is the first Latino in the post.
He told his party they faced a crisis of confidence after the election of Donald Trump, whom he said was the worst president in US history.
Mr Perez will face the tough task of trying to unite a party beset with lingering frictions between young progressive liberals who were sceptical of Hillary Clinton and the Democratic Party establishment, correspondents say.
“I am confident that when we lead with our values and lead with our actions we succeed. That is what the Democratic Party has always been about and that is what we will continue to be about”, Mr Perez told party delegates.
He said that while the 20 January inauguration of Mr Trump “was an undeniably important day”, the mass protests that followed were “far more important for America”.
Nevertheless he acknowledged that the Democratic party was “suffering from a crisis of confidence, a crisis of relevance”.
Mr Perez defeated Keith Ellison, a US representative from Minnesota, in a 235-200 second round vote.
Mr Ellison, the first Muslim elected to the US Congress, was backed by Senator Bernie Sanders.
He was swiftly made deputy chairman and urged party members to unite behind Mr Perez.
It was billed as a proxy battle between progressives and moderates in the Democratic Party. The political revolutionaries who supported Bernie Sanders in the 2016 primaries largely lined up behind Congressman Keith Ellison.
The establishment insiders who backed Hillary Clinton favoured former Labour Secretary Tom Perez.
There were even some fireworks reminiscent of that recently concluded nomination fight, with prominent voices on both sides threatening to leave the party if the opposition won.
In the end the establishment-backed candidate prevailed again.
Despite the drama, the Democratic committee chair is more behind-the-scenes organiser than ideological figurehead. With the party still stinging from its presidential defeat and extended drubbing at the state level in much of the US, Mr Perez faces a long, arduous job largely out of the spotlight.
He must kick-start the party’s fund-raising and recruit competent candidates for the 2018 midterm elections. He also has to lay the groundwork for the 2020 presidential nomination contest, which seems certain to be as contentious as it is wide-open.
If he succeeds, the winning candidates will receive the credit. If he fails, the axe will fall quickly on his neck. The stakes are high for Democrats, and the pressure on Perez to perform starts now.
