White House hopeful Joe Biden has called his poor performance in the Democrats' first 2020 leadership vote, in Iowa's caucuses, a "gut punch".
Mr Biden has come fourth, according to incomplete results from the election to pick a Democratic presidential nominee.
"I'm not going to sugarcoat it," Mr Biden said. "This isn't the first time in my life I've been knocked down."
With most results declared in Monday's glitch-plagued caucuses, Pete Buttigieg and Bernie Sanders are neck and neck.
But Mr Biden told an audience in New Hampshire: "I'm not going anywhere."
According to partial results from Iowa, the former US vice-president under Barack Obama has failed to pick up a single one of the delegates needed to clinch the Democratic White House nomination under America's quirky political system.
New Hampshire will be the next state to vote on 11 February in a string of nationwide votes culminating with the crowning of the party's presidential candidate in July.
Eleven contenders remain in the race to challenge President Donald Trump, a Republican, in November's election.
Iowa, which has long defended its position as the first race of the election year, was beset by problems when its app for reporting results crashed on Monday, spawning lengthy delays in results.
The Iowa caucuses present candidates with a golden opportunity to generate campaign momentum.
By Wednesday, 95% of precincts had reported:
- Mr Buttigieg, the former mayor of South Bend, Indiana, has 26.4% of the vote, awarding him 11 delegates
- Mr Sanders, a Vermont senator, has 25.7%, also with 11 delegates
- Massachusetts Senator Elizabeth Warren has 18.3% and five delegates
- Mr Biden has 15.8%, which leaves him with zero delegates
Those delegates will eventually represent these candidates when the Democratic nominee is chosen later this year.
Other candidates who failed to secure a single delegate include Amy Klobuchar (12.2%) and Andrew Yang (1%).
Iowa Democratic officials have said a "coding error" in the system caused the results delay, firmly rejecting suggestions that something more sinister, such as a hack or fix, might have swayed the outcome.
What else did Biden say?
On Wednesday, Mr Biden sharpened his attacks, targeting the two Democratic front-runners by name.
"We need a nominee who can help Democrats up and down the ticket," Mr Biden said.
He suggested that self-described democratic socialist Mr Sanders would be unelectable in a general election.
Mr Biden also said it would be a "risk" to nominate 38-year-old Mr Buttigieg, "someone who's never held an office higher than mayor of a town of 100,000 people".
Mr Buttigieg responded by saying "the bulk of the credit for the achievements of the Obama administration belong with President Obama".
Why did Biden come up short in Iowa?
By all accounts, Mr Biden failed to energise crowds to the extent that some of his rivals did in largely white, rural Iowa.
He has faced scrutiny for his verbal gaffes and his long and sometimes controversial political career, including his vote in favour of the Iraq war.
And Republicans have been hammering away at him for his son's lucrative board position with a Ukrainian natural gas firm at the time his father was US vice-president and in charge of American-Ukrainian relations, which came up in the Trump impeachment case.
Mr Biden, who remains the front-runner nationally, is hoping to shine in later primary contests with more diverse electorates, such as Nevada or South Carolina.