If you blinked, you might have missed it. Somewhere between Election Day and your 500th gulp of holiday-party red wine, Texas congressman Beto O’Rourke went from being the new darling of the left to its leading bête noire. Not much of substance actually changed in that time, of course. O’Rourke inspired many, but still lost his Senate race, and he’s now winding down his time in the House. What has changed is that O’Rourke, having built an $80 million grassroots political movement from scratch, is now seen as one of the top contenders for the Democratic presidential nomination. The polls bear this out: A recent Des Moines Register survey of Iowa placed him third among possible Democratic candidates, behind known commodities Joe Biden and Bernie Sanders.

O’Rourke is currently the biggest variable looming over the 2020 race, potentially the next-generation inspirational outsider that Democrats need to beat Donald Trump. He’s quietly meeting with prominent Democrats, including Barack Obama, and he’s filtering through an avalanche of texts and e-mails from operatives and activists begging him to run. The pro-Beto arguments are as much about process as about policy: yes, O’Rourke talked passionately about the issues that excite today’s Democratic Party—expanding Medicaid, banning high-capacity rifles, passing a DREAM Act. But he also found an authentic way to marshal support in non-traditional ways, leveraging social media to command attention, raise gobs of cash, and cut through Trump’s cultural saturation by presenting himself as a new kind of politician. Democrats across the country started to pay attention, and many of them want more.

The biggest thing that has changed in the Democratic discourse since November is that O’Rourke, sitting at home in El Paso, is accumulating power. That comes with pitfalls. As James Reston once said, power creates its own resistance.

The O’Rourke resistance happens to be coming from inside the house, or at least from the noisy neighbors. The Sanders wing of the Democratic Party, to the extent they identify with the party, is treating O’Rourke’s rise with some reasonable questions—what does this guy actually believe in?—and, in some cases, outright hostility. Still wounded from the insider anointment of Hillary Clinton in 2016 and her ultimate primary victory, they’re worried about a depressing sequel in which Sanders, again mulling a campaign, gets muscled out by powerful elites who want a more palatable centrist at the helm.

“People on the left that identify as Democratic socialist, the left that supports Sanders or Alexandria Ocasio-Cortez, for them, Bernie got robbed in 2016,” said Michael Kazin, the Georgetown University historian and co-editor of Dissent. “They think the Establishment is always looking for someone to go against Bernie—to run against progressives in the party and stop them from being ascendant. I think they are suspicious of Beto because he has taken oil and gas money, he’s becoming the darling of big donors, and Obama likes him.”

Being liked by Obama, who won two presidential elections and left office with an 90 percent favorable rating among Democrats, might not seem like a disadvantage in a Democratic primary. But to many on the left, Obama’s sins are plentiful: he bailed out Wall Street, half-assed the stimulus package and health-care reform, deported more undocumented immigrants than any president, and prosecuted drone warfare that left piles of civilian casualties across the Middle East. What especially chafes Sanders-style progressives is that Obama cloaked a centrist neoliberal agenda in a soaring, feel-good rhetoric that charmed voters and made them forget about all the bad stuff.