Minnesota Senator Amy Klobuchar will abandon her candidacy for the 2020 Democratic presidential nomination.
Senator Klobuchar came in a distant sixth place in Saturday's South Carolina primary.
Ms Klobuchar, 59, will join Joe Biden at his Dallas, Texas rally tonight to endorse the former vice-president, US media report.
The news comes on the heels of fellow moderate Pete Buttigieg suspending his campaign on Sunday.
Despite some strong debate performances and a surprise surge in the early primary voting state of New Hampshire, Ms Klobuchar failed to gain broader traction.
On the campaign trail, the Minnesota senator sold herself to moderate voters as the candidate who could win swing states back for the Democrats. However, her profile was largely eclipsed by centrist rivals Mr Biden, 77, and Mr Buttigieg, 38.
Ms Klobuchar's withdrawal comes on the eve of the so-called Super Tuesday primaries. On Tuesday, 14 US states will cast their votes to determine the Democratic presidential nominee.
With Ms Klobuchar's exit, five Democrats are left in the race to take on Republican President Donald Trump – Mr Biden, Bernie Sanders, Elizabeth Warren, Michael Bloomberg and Tulsi Gabbard. With the exception of Ms Gabbard, a Hawaii congresswoman, all are septuagenarians.
Seven delegates – representatives who will cast nominating votes for a candidate at the Democratic national convention in July – Ms Klobuchar had won from previous primaries are now free to vote for someone else. A candidate must win 1,990 delegates, gathered up from primary contests throughout the country, to win the nomination. Mr Sanders, the leftwing Vermont senator, currently leads the delegate count with 60 delegates, followed by Mr Biden with 54.
All aboard the Biden express
Seats on Joe Biden's campaign train are starting to fill up. Amy Klobuchar is heading to Dallas to share a stage with the former vice president on Monday night, while Pete Buttigieg is reportedly on the verge of announcing his endorsement as well.
The faceoff between Biden, the "establishment" candidate, and Bernie Sanders, the outsider, is taking shape – a contrast in styles and sensibilities that gives Democrats a clear choice between two directions to take the party.
It's not quite that simple, of course, as Elizabeth Warren seems set to stick around as a progressive-left alternative, while Michael Bloomberg continues to money-bomb his way into Super Tuesday.
Still, this represents a remarkable run of good fortune for Biden, who has been landing endorsements from Democratic politicians across the US the past few days.
Meanwhile, it may turn out that Sanders's big win in Nevada just over a week ago didn't give the VermonRead More – Source