Joe Biden’s presidential campaign was struggling amid debate gaffes, poor performances in early-voting states, and a crowded field.

But Biden received a series of high-profile endorsements on Monday – including from former rivals – just in time for Super Tuesday.

The endorsements are likely to boost his campaign and put new pressure on his competitors, as Sen. Bernie Sanders goes into the most important day of the primary retaining frontrunner status.

A late change in momentum may alter the mood on Super Tuesday, but it’s not clear how much it will help Biden.

Many voters will have made up their minds already – some literally in the form of early voting – and only the results will tell.

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Until former Vice President Joe Biden finally managed to win his first primary contest in three presidential runs, his 2020 Democratic presidential campaign was floundering.

He entered the race with frontrunner status and high expectations – but more recently started to suffer.

Setbacks included debates littered with unforced errors and dismal finishes in the Iowa and New Hampshire votes.

Bob Shrum, an adviser to Al Gore and John Kerry’s presidential campaigns, was not alone when he said Biden needed “a political miracle” to stay in the race.

But now – on the morning of Super Tuesday – the feeling around Biden’s campaign appears to have dramatically reversed, boosted by his victory Saturday in South Carolina and a quick succession of high-profile endorsements.

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Foto: Biden with his former rival Sen. Amy Klobuchar after she endorsed him during a campaign event in Dallas on Monday. Source: REUTERS/Eric Thayer

Biden’s campaign largely ranged from OK to abysmal

Biden entered the race as a household name, known for his close ties to President Barack Obama. It established him in the minds of many observers as one of the ones, if not the one, to beat.

He based his campaign around the idea that he was the one best suited to defeat President Donald Trump in a general election, but his perceived electability sagged as the months went by.

His debate performances, particularly early on, were roundly criticized and routinely ranked lower than those of his main competitors.

Rival candidates homed in on his record on race issues, and he made a series of bizarre comments including that he would “punch” domestic violence and that he had the support of the “only” African American woman in the US Senate, despite Sen. Kamala Harris, who is black, being onstage with him.

Foto: Pete Buttigieg endorsing Biden in Dallas on Monday. Source: REUTERS/Elizabeth Frantz

His performance in the first voting contests were also embarrassing for his campaign: He finished fourth in Iowa, fifth in New Hampshire, and second in Nevada.

Other problems facing Biden’s campaign included:

A collapse in support from African American voters – support the campaign leaned on heavily to make the case for Biden’s electability.

The entrance of Mike Bloomberg to the race, who spent hundreds of millions of dollars on advertising and is targeting the same centrist voters as Biden.

As time went on, one of his competitors, Sen. Bernie Sanders of Vermont, managed to cement his status as the frontrunner that at one time had appeared Biden’s by right.

But – as Super Tuesday dawned – his fortunes changed.

Biden won a string of high-profile endorsements in quick succession

Some of Biden’s former rivals threw their support behind him following his South Carolina victory.

These included Sen. Amy Klobuchar of Minnesota, who dropped out Monday, and former Mayor Pete Buttigieg of South Bend, Indiana, who dropped out Sunday.

Former Rep. Beto O’Rourke of Texas, who dropped out of the race in November, also endorsed Biden on Monday night – Texas has the second-most delegates of all the Super Tuesday states.

Foto: Beto O’Rourke embracing Biden after he endorsed him for president at a campaign event at Gilley’s in Dallas on Monday. Source: REUTERS/Eric Thayer

On Monday he was also endorsed by former Sen. Harry Reid of Nevada, once the most powerful Democrat in the Senate, and the former national security adviser Susan Rice.

Biden also received a crucial endorsement last week from Rep. Jim Clyburn, the most senior African American lawmaker in the House of Representatives and South Carolina’s most influential Democratic figure.

It not surprising that many of these figures, seen as moderates, would support another moderate.

But they turn up the heat on Biden’s remaining rivals, particularly Sen. Elizabeth Warren of Massachusetts, and put increased pressure on Sanders by consolidating the moderate vote.

Foto: Sen. Bernie Sanders of Vermont. Source: Scott Heins/Getty Images

Sanders has racked up endorsements from progressive Democrats and public figures, and he maintains frontrunner status with a slight plurality in pledged delegates.

On Monday night, he called for his former rivals’ supporters to join his campaign: “To all of Amy and Pete’s millions of supporters, the door is open. Come on in.”

A note of caution

Though the endorsements, dropouts, and general feel-good vibe around Biden may change the mood of some voters before polls close, it is also possible that the shift comes too late to make a difference.

Many of the states – especially California, with the most delegates – have large numbers of people who vote early and therefore would have already cast their ballot.

Also, old impressions die hard, and an endorsement by a candidate doesn’t mean all that candidate’s supporters will follow or that old impressions of a candidate will be forgotten.

As ever, it won’t be until Tuesday evening when results start to come in that we will know whether Biden’s last-minute boost mattered where it counts.