Democrats eager to put the brakes on Sen. Bernie Sanders in his quest to become the first democratic socialist to be their party's presidential nominee have a new strategy: pull people onto the Biden train.

Sen. Amy Klobuchar of Minnesota became the most high-profile Democrat to jump aboard, suspending her presidential campaign Monday and announcing she will appear with former Vice President Joe Biden at an evening rally in Dallas, where she will endorse him publicly. Her departure from the race follows that of former South Bend, Indiana, Mayor Pete Buttigieg, who suspended his campaign Sunday night and is reportedly preparing to endorse Biden.

Klobuchar's departure the day before Super Tuesday, when her home state will go to the polls, was surely a disappointment to the lawmaker who was considered a long-shot for the nomination but managed to survive a slew of other, more well-known Democrats.

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But it was also a sign that moderate Democrats are determined to join forces and deny the nomination to Sanders, who has a devoted following but whom many Democrats believe would lose to President Donald Trump and take the House majority with him.

"Biden is getting his lane pretty well cleared out," says Steven Schier, a political science professor at Carleton College in Minnesota. Progressive Sen. Elizabeth Warren of Massachusetts is "still in Bernie's way," and former New York City Mayor Michael Bloomberg is "the big imponderable," Schier adds. Bloomberg has spent a half billion dollars of his own $60 billion fortune on ads and campaigning in the hopes of a big showing on Tuesday.

Biden had been struggling in early contests, finishing fourth in Iowa, fifth in New Hampshire and a distant second in the Nevada caucuses, after Sanders. But a blowout win in South Carolina on Saturday night injected new energy, new money and new hope into the campaign of a man who made electability his central theme.

The former vice president had been expected to prevail in South Carolina, largely due to his support among African Americans, who make up almost 60% of the Democratic primary vote in the Palmetto State. He ended up winning every county, beating Sanders by nearly 30 percentage points and taking the lead in the overall popular vote, though still a handful of delegates behind Sanders.

That led to a desperately needed influx of $10 million to Biden's campaign, and a slew of high-profile endorsements started pouring in as well from officials in Super Tuesday states. They include state legislators, who are worried about losing seats ahead of post-2020 Census redistricting, as well as statewide officials and congressmen – especially those from swing districts that Democrats need to keep to retain their majority in the House.

In Virginia, Biden added to his list of supporters Rep. Jennifer Wexton, who flipped a red seat blue in 2018 and who had said she would not endorse anyone in the primary. She followed former Virginia Gov. Terry McAuliffe. Three former senators from the Super Tuesday state of Arkansas – Blanche Lincoln, Mark Pryor and David Pryor – have also endorsed their former Senate colleague.

Sen. Tammy Duckworth of Illinois, which votes March 17, announced her Biden endorsement Monday. Rep. Debbie Wasserman Schultz, former chairwoman of the Democratic National Committee, is among a slew of Biden backers in Florida, which also holds its primary that day.

While former President Barack Obama has not endorsed in the race, several of his Cabinet members have backed Biden, the most recent being former national security adviser Susan Rice on Monday.

Former Sen. Barbara Boxer of California, the biggest Super Tuesday state, endorsed Biden on Sunday. Biden on Monday also got the formal backing of freshman Rep. Veronica Escobar of Texas, the eighth Congressional Hispanic Caucus member to endorse the former vice president.

Escobar's endorsement is key because, while Biden has done well among African American voters, Sanders has drawn plurality support from Latinos, another important Democratic voter group. Hispanics will be important Tuesday in both California and Texas, both states where polls show Sanders in the lead.

However, there are indications that Biden's hugely successful weekend is having an impact among those voters as well.

A Morning Consult poll released Monday found that Biden's support among Latinos went up 9 percentage points, to 21%, as a first choice for the nominee. The same poll revealed that while Sanders is still in the lead in aggregate Super Tuesday states with 33% support across the 14 states, Biden's numbers went up 7 percentage points since his South Carolina win.

Klobuchar could help Biden in Minnesota, a state Sanders won overwhelmingly in 2016 against Hillary Clinton in that year's primary, Schier says. Klobuchar has been leading in Minnesota polls, but just by 4% or 5%, he says.