On Sunday, Sen. Amy Klobuchar (Minn.) announced she’s running for the Democratic presidential nomination. One of Klobuchar’s biggest strengths is her appearance of electability: She often posts sky-high margins when she runs in statewide races, and she appears to be liberal enough to win a primary but not so liberal that Democrats would be skittish about running her in the general election. At a cursory glance, Klobuchar is a great candidate for the modern Democratic Party — experienced, possessed of a strong winning record, well to the left of the political center and, frankly, not a white man.

But being perfect on paper doesn’t always translate into being perfect in practice. Klobuchar, like her competitors for the Democratic nomination, is heading into the phase of the campaign where reporters, analysts, opposition researchers, interest groups and more will be digging up dirt on all of the top tier candidates. In fact, that process has already started with Klobuchar: According to reports in HuffPost and BuzzFeed, former staffers have recently said that she has a history of humiliating and mistreating her team members and creating a generally tough work environment.

It’s not clear that this news alone will sink Klobuchar. It’s still early, and she wouldn’t be the first intense boss to become president. But this kind of story, and the primary campaign as a whole, can be bruising. That’s the entire point of the process — or at least, before the Trump era, it was supposed to be.

At various points in the 2012 cycle, a number of different candidates surged ahead of Mitt Romney in national polls, only to fall apart when reporters and their opponents put them under the microscope. In their book “The Gamble,” John Sides and Lynn Vavreck described this process as “Discovery, Scrutiny, Decline” — in which a candidate catches fire in the media, gains in the polls but fails to survive once they’re in the spotlight.

Then-Texas Gov. Rick Perry is probably the best example of this. Perry was solid on paper — he was a sitting governor from a large state who arguably had a better record of conservative orthodoxy than Mitt Romney (who ran as a moderate-to-liberal Republican in Massachusetts). But he flopped in the debates. His stance on immigration — he signed a bill that let undocumented immigrant children get in-state tuition at state universities and later said opposing such a measure was heartless — caused him to lose support with a Republican base that had soured on immigration. And in his famous “oops” moment, Perry forgot which government agency he had proposed to eliminate.

The other 2012 candidates were less plausible nominees than Perry and Romney, but they also illustrate how the harsh light of scrutiny can shrivel a reputation. Pizza mogul Herman Cain surged after a good straw poll and helpful debate performances but fell when multiple women accused him of sexual harassment. Former House speaker Newt Gingrich surged after Cain fell, but his opponents managed to knock him down by talking about his personality flaws and ties to the Federal Home Loan Mortgage Corporation, a.k.a. Freddie Mac.

And scrutiny doesn’t just knock off long-shot Republicans. Joe Biden faced a plagiarism scandal back in 1987. Gary Hart was a serious Democratic candidate for the 1988 election, but journalists reported that he had an extramarital affair.

It’s true that the primary process doesn’t weed out every flawed candidate.

From wearing blackface to having inappropriate physical contact, people who serve in public office must meet a higher standard of repentance. (Joshua Carroll/The Washington Post)

In 1992, Bill Clinton was hit hard by reports of an extramarital affair but managed to come back and win the nomination and presidency. In 2016, Hillary Clinton cleared the field early and managed to win despite the issues with her email servers. Donald Trump played a complex media game where he leaned into his problems, kept other Republicans from getting airtime and consolidated his base while his opponents fought over pieces of the anti-Trump pie. And on the state level, Ralph Northam somehow made it through a primary and a general-election campaign without anyone unearthing a racist photograph from his yearbook spread.

Though stories like the HuffPost and BuzzFeed reports might irk Klobuchar fans, anyone who is rooting for a Democratic candidate to beat President Trump ought to be in favor of a long, tough, thorough primary.

Romney wasn’t the most inspiring nominee the Republican Party ever produced, but he didn’t have the same baggage that Cain, Gingrich, Perry and others had. The primary process gave voters time to temporarily jump on the bandwagon of an exciting new candidate, learn that they were either scandal-prone or ideologically out of step, and jump off before it was too late.

Hillary Clinton won the 2016 primary, but the strength of Sen. Bernie Sanders’s out-of-nowhere challenge was (or at least should have been) a signal that something — whether it was her ethical issues, her platform or just the fact that she had to drag Bill and his drama around — was off. In retrospect, a tougher process (i.e. one that included another mainstream Democrat like Biden or Kirsten Gillibrand) might have produced a stronger nominee and a Democratic president.

And if the 2016 Republicans had focused less on each other, consolidated behind a strong non-Trump candidate early and aimed at Trump, they might have nominated someone who would have won by more and had a better chance at a second term. A small segment of party loyalists might decide not to turn out if their candidate lost a long primary, but that seems like a small price for a more thoroughly vetted nominee.

It’s way too early to know whether Klobuchar will share the same fate as these other candidates. She might catch fire early and waltz through the primary and the general election scandal-free. Maybe sharp public scrutiny of the way she treated her staff as a senator would lead her to behave differently as a candidate and as president of the United States, thus avoiding some of the turmoil and turnover that have defined Trump’s presidency.

Either way, people who care about having the best possible president should root for a competitive, thorough primary. The Democratic nominee will have at least a 50 percent shot of being the president in 2020 — so it’s good for the party and the country to know as much about them as possible as early as possible.