Minnesota Senator Amy Klobuchar ended her Democratic presidential campaign on Monday and will reportedly endorse rival Joe Biden in an effort to unify moderate voters behind the former vice president's White House bid.

She is flying to Dallas and plans to join Biden at his rally on Monday night. Pete Buttigieg, who withdrew from the race over the weekend, will also reportedly attend the rally and endorse Biden as well.

Klobuchar outlasted several better-known and better-funded Democrats, thanks to a better-than-expected third-place finish in New Hampshire. But she could not turn that into success elsewhere, as she struggled to build out a campaign that could compete across the country and had poor showings in subsequent contests.

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The three-term senator had one of this cycle's more memorable campaign launches, standing outside in a Minnesota snowstorm last February to tout her "grit" and Midwestern sensibilities. Klobuchar argued that her record of getting things done in Washington, DC, and winning even in Republican parts of her state would help her win traditionally Democratic heartland states like Wisconsin and Michigan that flipped in 2016 to give Donald Trump the presidency.

She was hoping to own the moderate lane of a Democratic field that grew to some two dozen candidates. But that got much tougher when Biden joined the race in April, starting as a frontrunner and remaining there until Bernie Sanders started winning the early contests. Klobuchar also was quickly overshadowed by Pete Buttigieg, a fellow Midwesterner who shot from being the largely unknown mayor of South Bend, Indiana, to a top contender on a mix of intelligence, strong oratory and youthful optimism.

Buttigieg dropped out on Sunday, saying he no longer had a viable path to the nomination.

Low name recognition

Klobuchar entered the race with low name recognition compared with many of her rivals, a disadvantage she was still citing a year into her campaign. Outside Minnesota, the lawyer and former prosecutor was best known for her questioning of Supreme Court nominee Brett Kavanaugh during a 2018 Senate Judiciary Committee hearing.

Even before she got into the race, Klobuchar was hit with news stories claiming she mistreated her Senate staff, and she had a higher-than-usual turnover rate in her office. Klobuchar said she is a "tough boss" but countered that she has several longtime employees, including the manager of her presidential campaign.

She also faced questions over her prosecutor past. In January, The Associated Press news agency published a story about Klobuchar's office in Minneapolis having prosecuted the case of a black teenager accused of the 2002 shooting death of an 11-year-old girl. Klobuchar has cited the story to show her toughness on crime. But an AP/APM Reports investigation uncovered new evidence and myriad inconsistencies, raising questions about whether Myon Burrell was railroaded by police. The issue followed Klobuchar on the campaign trail, with protesters forcing her to cancel a rally in suburban Minneapolis days before Super Tuesday.

Klobuchar campaigned on her productivity in Washington, where she led more than 100 bills that were signed into law. And she criticized the more liberal candidates in the field, Senators Sanders and Elizabeth Warren, for running on promises she said they could not keep.

Rather than advocate for Medicare for All, for example, Klobuchar favored expanding the Affordable Care Act and working to reduce prescription drug costs - changes she said had a chance of passing and would make a significant impact. She supported making community colleges free but said she wouldn't promise to do the same for four-year colleges and universities because the US cannot afford it.

"I've got to tell the truth," she said during a CNN town hall at a college campus, where she acknowledged her position may be unpopular with younger voters.

Fundraising shortfalls

Klobuchar was one of the first candidates to outline a plan for addressing addiction and mental health, an issue she described as personal because of her father's longtime struggle. Her accounts of growing up with a father suffering from alcoholism and watching him be forced to choose between prison or treatment were some of the most compelling moments of speeches, interviews and discussions with voters. Klobuchar said that her father described getting help as being "pursued by grace" and that it's an opportunity all people fighting addiction deserve.

But Klobuchar couldn't match her top competitors in fundraising. She raised about $11m in the last quarter of 2019 - roughly half of what Sanders and Buttigieg received. The lack of finances early on in the campaign meant Klobuchar was not able to expand her operation on the ground in Iowa and New Hampshire until months after her rivals. She then scrambled to put an operation in place in Nevada, South Carolina and the 14 states that voted on Super Tuesday.

Still, there were bright spots, including strong debate performances that helped bring in new donors. Her campaign credited Klobuchar's showing in a debate days before the New Hampshire primary with helping her clinch a better-than-expected third place in the state's primary, topping Warren and Biden. Klobuchar said she raised $12m in the next week.

During one debate she addressed sexism in the campaign, questioning whether a woman with Buttigieg's experience would qualify for the stage. She also pushed back at fears of a female candidacy, saying, "If you think a woman can't beat Donald Trump, (House Speaker) Nancy Pelosi does it every day."