Now that former Vice President Joe Biden is the presumptive Democratic presidential nominee, the search for his running mate is on and Sen. Amy Klobuchar, D-Minn., is one of the most popular names mentioned as a possible VP.

Klobuchar gained widespread respect in the Democratic party and increased her name recognition nationally as she ran a competitive campaign for the 2020 Democratic presidential nomination.

Here are five things to know about one of the top contenders in the 2020 veepstakes.

Democratic presidential candidate Sen. Amy Klobuchar, D-Minn., speaks at her election night party, Tuesday, Feb. 11, 2020, in Concord, N.H. (AP Photo/Robert F. Bukaty)

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She was rated the most effective Democratic senator

A Vanderbilt study released in February 2019 ranked Klobuchar as the most effective Democratic senator along with Sen. Chuck Grassley, R-Iowa, as the most effective Republican senator. None of the other Democratic senators who ran for president ranked in the top 10.

The study measured members' effectiveness based on the number of bills they sponsor, how far those bills advance and the bills' significance, among other factors.

She's painted herself as a moderate Democrat like Biden

A senator from a purple state, Klobuchar has always been careful to not use divisive, liberal rhetoric in her campaigns.

In February, it came out that Klobuchar had called for a border fence in 2006. In January it was reported that she called for "reducing abortions" in a 2006 interview — though she made clear at the time that she was pro-choice.

Klobuchar in many ways appears to be a good fit with Biden, who supported the controversial Hyde Amendment that blocks federal funding for abortion until last year. They are both dealmaking moderate Democrats who either previously were or are currently in the Senate -- an intersection that made them rivals during the Democratic primary race.

In fact, the high-point in Klobuchar's campaign was the low point of Biden's -- Klobuchar finished in a surprising third place in New Hampshire as Biden finished in fifth in the state. But a lack of money for Klobuchar and high-support among minorities in Nevada and in the South for Biden turned the tide of the race, allowing Biden to begin running away with the nomination by Super Tuesday.

Sen. Amy Klobuchar, D-Minn., endorses Democratic presidential candidate former Vice President Joe Biden at a campaign rally Monday, March 2, 2020 in Dallas. (AP Photo/Richard W. Rodriguez)

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Her endorsement was critical to Biden's primary win

Klobuchar was the third Democratic presidential candidate to drop out of the race after Biden's dominating win in South Carolina, following billionaire Tom Steyer and former South Bend, Ind., Mayor Pete Buttigieg. But when Klobuchar exited the race the day before Super Tuesday, she immediately endorsed Biden, becoming the first serious presidential contender to exit the race and back the former Vice President.

Klobuchar's endorsement set off an avalanche of support for Biden, and was quickly followed by endorsements of Biden from Buttigieg, former Texas Rep. Beto O'Rourke and former Senate Majority Leader Harry Reid, among many others.

After Biden's 10-win Super Tuesday, there was no stopping the candidate as he went on to extend his delegate lead over Sanders significantly in subsequent contests.

She interned for former Vice President Walter Mondale

If Klobuchar is the next Vice President of the United States, it won't be her first time working in a vice president's office.

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As a college student, Klobuchar was an intern for former Vice President Walter Montale under the Carter administration.

Though she says she "was assigned to inventory all the office furniture," Klobuchar said she learned from the experience.

"Do good work no matter the assignment & listen to wise mentors," she said in a tweet honoring Mondale's birthday.

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She's been accused of mistreating her staff

Huff Post reported in early 2019 that some former staffers of Klobuchar's said she verbally demeaned them, made one aide cry after being late and had staff take care of personal tasks like getting her dry cleaning. Additionally, BuzzFeed reported that Klobuchar had thrown office supplies, including a binder, at staffers.

The Huff Post report noted that three candidates for senior positions in her campaign withdrew from consideration for the jobs, partially because of Klobuchar's history with staffers.