Senior US Democrat suffers shock defeat to 28-year-old newcomer in New York as party's splits exposed

The US Democratic Party's internal divisions were laid bare on Tuesday when establishment congressman Joe Crowley was ousted by a 28-year-old far-left political novice.

Mr Crowley, who until Tuesday had been considered a candidate to replace Nancy Pelosi as party leader, lost the first competitive primary he had faced in more than a decade to Alexandria Ocasio-Cortez, a former aide to the late Massachusetts Senator Ted Kennedy.

It was the first defeat of the primary season for a Democratic incumbent and it strongly suggested that lingering splits between the Democratic Party's pragmatic and more liberal wings might be widening in the early years of the Trump presidency.

"Perhaps he should have been nicer, and more respectful, to his President!" Mr Trump tweeted, taking credit for a victory by a candidate more liberal than Crowley.

History suggests that Mr Trump's Republican Party, like the parties of virtually every first-term president dating back to Ronald Reagan in 1982, will suffer losses this autumn.

Yet Mr Crowley's loss suggests that Democrats must overcome intraparty divisions if they hope to take control of Congress and key governors' offices nationwide.

After conceding the race, Mr Crowley said he would support Ms Ocasio-Cortez in the general election.

"The Trump administration is a threat to everything we stand for here in Queens and the Bronx, and if we don't win back the House this November, we will lose the nation we love," Mr Crowley said in a statement.

In New York, Ms Ocasio-Cortez ran as a working-class daughter of an immigrant, casting Mr Crowley as elitist and out of touch with the community.

"These results are also a shot across the bow of the Democratic establishment in Washington: a young, diverse, and boldly progressive Resistance Movement isn't waiting to be anointed by the powers that be," said Matt Blizek, of MoveOn, which backed Crowley's challenger.

Cynthia Dixon, the Sex and the City actress who failed to secure the Democratic party's support for her campaign for governor of New York state last month, said "the progressive revolution has begun".

"We endorsed (Ocasio-Cortez) because we believe she is the future of the Democratic Party. Today, she ousted 10-term incumbent Rep. Joe Crowley. Here in New York, the progressive revolution has begun, and we could not be more proud to be a part of that movement," she tweeted.

It was a successful night for the US president, who saw all three of his endorsed candidates survive primary challenges that could have embarrassed him and the party.

Those included former Republican presidential nominee Mitt Romney, who once branded Mr Trump "a fraud" but has changed his tune in the past two years.

But none of the day's contests mattered more to Mr Trump than the one in South Carolina. Gov. Henry McMaster, one of the president's earliest and strongest supporters, survived an unusually tough challenge from a political newcomer, self-made Republican millionaire John Warren.

The White House went all-in for the governor in recent days, dispatching the president and the vice president to the state in an effort to prevent a political debacle.

Voters in Colorado, Maryland, Mississippi, New York, Oklahoma, South Carolina and Utah picked candidates on Tuesday for the November 6 midterm elections that will determine whether Republicans maintain control of both chambers of the US Congress as well as numerous gubernatorial seats.

Democrats need to flip 23 of 435 seats to take over the House of Representatives, which would stymie much of Mr Trump's agenda while likely opening up new avenues of investigation into his administration. They would have to net two seats to take the Senate, but face longer odds there.