Minnesota Nice Wasn’t Enough. Neither were Sen. Amy Klobuchar’s center-left positions and bland presentations. And so, today, she left the race for president. Why?The immediate reason is that her chances of winning anything on Super Tuesday were grim. The only exception was her home state, and it was far from certain. Klobuchar’s failures at the ballot box meant she had no plausible path forward. Her donors would stop giving and her backers would begin blaming her (and other also-rans) for blocking Joe Biden, who they now see as the only center-left candidate with a shot at the nomination. Biden’s huge victory in South Carolina and Bloomberg’s disastrous debates cemented that position. Party insiders are desperate for an alternative to Bernie Sanders. They would rather go to a meet-and-greet in Wuhan than see an avowed socialist at the top of the ticket. Those pros have solid reasons for their fear. First, they think Sanders would devastate their down-ballot candidates, jeopardizing their chances to keep the House and retake the Senate. They could be wrong, just as Republican insiders were in 2016, but they are convinced Bernie would pose impossible obstacles for centrist Democrats across the country. Second, Bernie would assault the insiders hold on lucrative lobbying contracts and policy influence, just as Trump’s victory smacked down the K Street Republicans, the US Chamber of Commerce, and traditional Republican think tanks.bannerWith Bernie poised to win the biggest Super Tuesday prizes, California and Texas and perhaps others, he is closing-in on the Golden Ring: an insurmountable lead going into the Democratic Convention in Milwaukee. But he hasn’t nailed it down yet. That’s why insiders will exert all their remaining leverage on low-ranking candidates, such as Klobuchar, to get out of the race — and do it now. They’ll also urge endorsements of Biden, while those can still help. Klobuchar’s announcement that she will back him makes her an obvious VP candidate on his ticket.Why did Klobuchar never gain traction with the broader Democratic electorate? The most important reason was that she was simply too milquetoast for activists who are fanatical about defeating Trump. She never matched their frenzy. Second, she never developed ties to the minority communities that are crucial to the Democratic coalition. By contrast, Biden has strong ties to African Americans, especially older, established politicians like Rep. Jim Clyburn, whose backing was vital to Biden’s win in South Carolina. Of course, Biden’s stature as Barack Obama’s vice president is the other pillar of his support in the African American community. (Meanwhile, Bernie Sanders seems to hold an equally strong position among Latinos, according to the vote in Nevada and polls in other states.)Klobuchar’s exit and endorsement won’t shift many votes to Biden. She doesn’t have many to shift. But, together with Pete Buttigieg’s exit and Bloomberg’s failure at retail politics, it establishes Biden as the one candidate to stop Bernie. The question is whether Joe, with his gaffes, goofiness, and geologic age, has enough gas left in the tank to stop the Democratic party’s socialist surge.Charles Lipson is the Peter B. Ritzma Professor of Political Science Emeritus at the University of Chicago, where he founded the Program on International Politics, Economics, and Security.