U.S. Sen. Amy Klobuchar is ending her presidential campaign and is prepared to endorse Vice President Joe Biden.

Klobuchar is expected to make the announcement Monday evening.

Klobuchar failed to win a single primary in her bid for the Democratic White House nomination. She finished fifth in the nationally ridiculed Iowa Democratic caucus, but placed a surprising third in New Hampshire, fueling hopes she could sustain a successful run.

However, she followed New Hampshire with a sixth-place finish in Nevada and a distant sixth in Saturday's South Carolina primary.

The Minnesota senator ended her campaign only hours before Super Tuesday, the nation’s biggest presidential primary. A total of 14 states are holding their primaries on Tuesday, including Minnesota, where 75 delegates are up for grabs.

»State by state breakdown of Super Tuesday delegates

On Sunday, a Klobuchar rally in Minnesota was cancelled after protesters occupied a stage on which the candidate was set to appear. The protesters were rallying on behalf of Myon Burrell, a Minnesota teenager who was sentenced to life in prison under then-County Attorney Klobuchar for murder.

Protesters were affiliated with the Racial Justice Network, Minneapolis NAACP and others took the stage in Burrell's honor chanting "Free Myon" and "black lives matter."

Klobuchar follows Indiana Mayor Pete Buttigieg, who ended his campaign on Sunday following South Carolina’s primary, and billionaire Tom Steyer, who dropped out late Saturday night following his Palmetto State loss.

Buttigieg is also expected to endorse Biden, according to reports.

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

Super Tuesday is set for March 3. Fourteen states will be holding presidential primaries in 2020's biggest election so far. They are Alabama, Arkansas, California, Colorado ... Maine, Massachusetts, Minnesota, North Carolina ... Oklahoma, Tennessee, Texas, Utah, Vermont and Virginia. American Samoa is also voting, as are Democrats Abroad, the Democratic party affiliate for American citizens living outside the U.S. With California and Texas as two of the nation's most populous states, more than one thi

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 front-runner and remaining there.

Klobuchar also was quickly overshadowed by 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.

Here are 2020's important election dates. Iowa causes - 2/3. New Hampshire primary - 2/11. Nevada caucuses - 2/22. South Carolina primary - 2/29 Super Tuesday - 3/3 Idaho, Michigan, Mississippi, Missouri, & Washington primaries, N.D. caucuses - 3/10. Arizona, Florida, Illinois & Ohio primaries - 3/17. Georgia primary - 3/24 Alaska, Hawaii, Louisiana primaries & Wyoming caucuses - 4/4. Wisconsin primary - 4/7. Connecticut, Delaware, Maryland, New York, Pennsylvania & Rhode Island primaries - 4/28  Kansas

Klobuchar's decision came in the midst of a three state swing on the eve of Super Tuesday, as Klobuchar had held a morning campaign stop in Utah, and was later scheduled to go to Colorado and Tulsa, Oklahoma.

Klobuchar tried to offer herself as the alternate to Biden in the more moderate lane of the Democratic Party, often restricting her comments to jabs at President Donald Trump.

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.