Fellow lawmakers – including his opponents for the Democratic presidential nomination – have put politics aside to wish him a full and speedy recovery.
"During a campaign event yesterday evening, Sen. Sanders experienced some chest discomfort. Following medical evaluation and testing he was found to have a blockage in one artery and two stents were successfully inserted," said Sanders' senior adviser Jeff Weaver on Wednesday in a statement.
"Sen. Sanders is conversing and in good spirits. He will be resting up over the next few days," Weaver said. "We are canceling his events and appearances until further notice, and we will continue to provide appropriate updates."
Several presidential candidates, including former Texas Rep. Beto O'Rourke, former Secretary of Housing and Urban Development Julian Castro and California Sen. Kamala Harris, were quick to voice their well-wishes, with many sending tweets to that effect.
"Wishing @BernieSanders a full and speedy recovery," O'Rourke tweeted. "Our thoughts are with you and your family today-- and I look for ward to seeing you back out on the campaign trail soon."
Castro echoed those sentiments, writing on Twitter, "Our whole team has you in their thoughts."
"Oh no. Stay strong Bernie," tweeted candidate Andrew Yang, along with a prayers hand and American flag emojis.
South Bend, Indiana, Mayor Pete Buttigieg said his campaign is "sending our best" and "thinking of him and his family today, and I look forward to seeing him back on the campaign trail very soon."
Buttigieg told ABC News later in the day that his team was "reaching out to send good wishes. I'm not sure what he needs right now is a visit from somebody like me, but definitely want to let him know that we're thinking of him and wishing him a speedy recovery."
Former Rep. John Delaney of Maryland tweeted that he and his wife, April McClain-Delaney, sent their "prayers" to Sanders, adding, "His fighting spirit will sustain him during this time, as will the support and love of his family, friends and countless supporters."
Former Vice President Joe Biden, a fellow 2020 Democratic presidential front-runner, also tweeted words of support.
"@DrBiden and I are sending our best wishes to @BernieSanders, Jane, and the whole Sanders family. Anyone who knows Bernie understands what a force he is. We are confident that he will have a full and speedy recovery and look forward to seeing him on the trail soon."
GOP contender Joe Walsh sent "prayers for a successful procedure and a very quick recovery."
Liberal activist and billionaire candidate Tom Steyer also wished Sanders a "quick and easy recovery," on Twitter.
Sanders' colleagues from both the campaign trail and the Senate also sent their well-wishes.
She told a crowd at a Las Vegas event this morning that she has been in touch with Sanders, as well.
"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," Warren. "So, thank you. I've called, I've texted and I'll send your best wishes if that's OK with everyone,"
"Glad to hear my friend @BernieSanders is doing well and in good spirits—wishing him a speedy recovery," Sen. Cory Booker tweeted.
"If there's one thing I know about him, he's a fighter and I look forward to seeing him on the campaign trail soon," Harris wrote.
"Bernie's fighting spirit will get him through anything and everything," Sen. Amy Klobuchar tweeted. "Good to hear he is doing better and look forward to seeing him soon."
Klobuchar also started her Wednesday afternoon appearance on MSNBC with well wishes to Sanders.
"Can I say first, my thoughts right now are with Sen. Bernie Sanders. We came into the Senate together, served together in leadership. His fighting spirit, I know, will get him through this," Klobuchar said. "From all reports, he's doing well right now but it was a shock, I think, for everyone to wake up to hear that. And we are just thinking of him today. I know we'll see him back out on the campaign trail."
Hawaii Rep. Tulsi Gabbard heard of the news right before talking to the press at an event in New Hampshire this morning. She told Sanders to "take a break and get better."
"Gosh, you know, my heart and prayers are out to him and Jane and their whole family, and I hope for a his very quick and swift recovery," she said.
Gabbard recalled when in 2016, Sanders had a cold but didn't want to take a break from the trail.
"Bernie does what Bernie wants to do. And again, I really hope that this is a moment that he just stops and pauses and makes sure he takes care of his health," Gabbard said.
The director of communications for President Trump's reelection bid also sent well wishes on behalf of the campaign.
Sanders' 2016 Democratic opponent, former Secretary of State Hillary Clinton, also extended her positive thoughts on a Wednesday appearance on "The View."
"We wish him and hope for the best," Clinton said, having just heard the news.
Clinton's daughter, Chelsea Clinton, added praise for Sanders for getting treatment, saying, "I am so grateful that Senator Sanders had a chest pain yesterday and immediately went to the doctor which is what we hope any man in our lives would do. Thank you for being a good example."
Former GOP candidate for president and Sen. Ted Cruz said he and his wife, Heidi, "are lifting up Bernie in prayer."
This is a developing story. Please check back for updates.