On Wednesday, Bernie Sanders’s campaign announced that the Vermont senator had undergone surgery for an arterial blockage and would cancel all future events until further notice. According to senior adviser Jeff Weaver, the 78-year-old Sanders experienced chest pain at an event in Nevada, and had two stents installed during a common emergency procedure. Weaver said Sanders was “conversing and in good spirits,” and will be “resting up over the next few days” before returning to the campaign trail. It is not immediately clear whether this will impact his upcoming appearance at the October 15 presidential debate.

Almost instantly, Twitter was flooded with well-wishes from Sanders’s fellow 2020 Democratic hopefuls, including Kamala Harris and Elizabeth Warren. “Wishing Senator @BernieSanders a quick and speedy recovery!” wrote Lindsey Graham.“Thinking of @BernieSanders as he recovers today,” tweeted Rep. Ilhan Omar. As she took the stage in Las Vegas, Warren said, “I assume you’ve heard the news about Bernie—that he’s had a medical incident. And I know everyone here wishes him well, wants to see him strong and back on the trail as soon as possible.”

Sanders has been polling near the top of the Democratic primary field, vying with Warren for second place to front-runner Joe Biden. The day before his surgery, Sanders’s campaign announced it had raised a staggering $25.3 million in the most recent quarter, raking in 1.4 million donations from donors who had yet to max out their contribution limits. Still, sporadic observers have remarked that Sanders is stagnating while Warren is surging—a narrative that has taken hold in some corners. “They don’t know where they’re going,” a Democratic activist with knowledge of the Sanders campaign told Politico recently, of Sanders’s sweep through Iowa. “They know things aren’t going well, and they’re grasping at ideas.”

Sanders’s camp, however, is quick to counter this narrative. “The most important thing is person-to-person contact, all right?” Sanders recently told a 2016 delegate who asked him about his primary strategy. “It is everybody here reaching out to five other people and explaining to them the importance of the election and why you think I should win this election.”

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