US Democratic presidential candidate Joe Biden has picked up three endorsements from former rivals on the eve of the most important day in the 2020 White House race so far.
Amy Klobuchar, Pete Buttigieg and Beto O'Rourke all campaigned with the former US vice-president in Dallas, Texas.
On Super Tuesday, voters in 14 states will pick their preferred Democratic candidate for November's election.
The Democratic frontrunner remains the left-wing senator, Bernie Sanders.
Democratic moderates have been calling on party figures to urgently unite to stop Vermont Senator Bernie Sanders, a self-described democratic socialist, from becoming the party's nominee to take on President Donald Trump, a Republican.
The other candidates still in the race are Elizabeth Warren, Michael Bloomberg and Tulsi Gabbard. With the exception of Ms Gabbard, a Hawaii congresswoman, all of the Democratic hopefuls are septuagenarians.
What did Biden's new backers say?
Ms Klobuchar, a Minnesota senator, suspended her campaign and endorsed Mr Biden on Monday.
Appearing alongside Mr Biden on Monday night, she said: "If we spend the next four months dividing our party and going at each other, we will spend the next four year watching Donald Trump tear apart our country."
Mr Buttigieg, a former mayor from Indiana who dropped out of the race on Sunday, said at another event with Mr Biden: "I'm looking for a leader, I'm looking for a president, who will draw out what's best in each of us."
Mr Biden, 77, told reporters that Mr Buttigieg, 38, "reminds me of my son Beau", who died in 2015.
Former US congressman Mr O'Rourke, who dropped out of the race last November, also appeared on stage with Mr Biden.
Ms Klobuchar and Mr Buttigieg had both been competing with Mr Biden for the same pool of pragmatic, centrist Democratic voters.
Both stepped aside following Mr Biden's overwhelming victory in South Carolina at the weekend, which came after he struggled in the first three Democratic leadership contests this year.
Earlier on Monday, Mr Biden also picked up endorsements from former Obama National Security Adviser Susan Rice, former Senate leader Harry Reid and several members of Congress.
Who else is still in the race?
Five contenders remain out of a Democratic field that once featured more than two dozen.
Among them is New York billionaire Mike Bloomberg, who is also pitching to moderate Democratic voters.
The former mayor of New York City – who will appear on a 2020 ballot for the first time on Tuesday – has invested more than a half billion dollars in his presidential bid.
Mr Bloomberg told a Fox News town hall on Monday that the nominee could ultimately be chosen through "horse-trading" at the Democratic convention in Milwaukee, Wisconsin, in July.
Also still in the race are Massachusetts Senator Elizabeth Warren and US congresswoman Tulsi Gabbard of Hawaii.
How did Sanders react?
Campaigning in Minnesota on Monday night, Mr Sanders invited his rivals' supporters to join his campaign.
"To all of Amy and Pete's millions of supporters, the door is open. Come on in," Mr Sanders said.
His campaign suggested the party's big money donors wanted to stop the Vermont senator.