Pete Buttigieg entered the 2020 race as a longshot. But the 37-year-old South Bend mayor has since demonstrated exceptional staying power, captivating moderates and many in the donor class, and establishing himself as part of the top tier of candidates. Now, he’s doing more than surging in polls; he’s starting to lead them. A Des Moines Register/CNN poll over the weekend showed Buttigieg as the Democratic frontrunner in Iowa by a comfortable margin. Among those surveyed in the caucus state, 25% said Buttigieg is their first choice, leading his closest competitor by almost ten points. Elizabeth Warren was second, at 16%, followed by Joe Biden and Bernie Sanders, both at 15%.

It was a stunning development, representing a 16-point boom for Buttigieg over the last two months and suggesting that he could be the candidate to beat in the Hawkeye State. While that surely sends a jolt through the other Democrats vying for the party nod, it has also sounded alarms among Republicans. “He’d be a fresh face with a message of unity and a more traditional Democratic program that’s not as scary to suburbanites,” Karl Rove told Axios Monday. Some top Trump advisers are reportedly worried that Buttigieg is “more talented than Joe Biden” and “will be harder to brand as a leftist radical.” A source close to the president’s campaign told Axios that Buttieg “might be better for them to win Wisconsin than Warren...and I think it comes down to Wisconsin right now.”

Buttigieg’s star has risen in tandem with increasing concern among the party establishment that Biden is carrying too much baggage to defeat Donald Trump, and that Warren and Sanders are too far left. Buttigieg has appealed to the party’s moneyed centrists by taking a middle-of-the-road approach, relying less on a bold agenda and more on soaring rhetoric evoking Barack Obama’s calls for unity. “We will fight when we must fight,” he said during a barnstorming trip to Iowa earlier this month. “But I will never allow us to get so wrapped up in the fighting that we start to think fighting is the point. The point,” he added, “is what lies on the other side of the fight.”

Such appeals have earned him large crowds, growing support, and the attention of big donors. But they’ve also rankled other Democrats, who’ve bristled at what they see as empty rhetoric. Beto O’Rourke, who has since dropped out, saw Buttigieg as a “human weather vane,” the New York Times reported this month. Amy Klobuchar, who was sitting in fifth in last weekend’s Iowa poll, has said that a female candidate with Buttigieg's level of experience would not be taken as seriously as he's been. When Buttigieg suggested that Warren’s agenda was divisive, she shot back: “I’m not running some consultant-driven campaign with some vague ideas that are designed not to offend anyone.” Many of Buttigieg’s detractors view his approach as an inadequate response to an openly corrupt president who’s left some Americans feeling uniquely vulnerable. He’s invited serious questions about his ability to tackle those issues, struggling to make inroads among black and minority voters.

That could weigh Buttigieg down in the early primary state of South Carolina. But a win in Iowa, the first contest of the Democratic primary, could deliver him significant momentum, forcing the political world to take him seriously, and potentially damaging the campaigns of the other leading candidates. A Buttigieg victory, after all, would raise questions both about Biden’s electability—his primary selling point—and the electorate’s appetite for the progressive visions of Warren and Sanders. With plenty at stake, Buttieg may start getting the frontrunner treatment—particularly at Wednesday night’s Democratic debate.

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