The announcement comes after a Clinton-aligned super PAC suggested it would call on the 74-year-old Vermont senator to verify his health, and one day before the fourth Democratic debate, held in Charleston, South Carolina.
The letter, Jeff Weaver said, would prove Sanders -- the oldest candidate in the presidential field who also would be the oldest president to take office -- is in "excellent health."
The Sanders campaign's decision came after David Brock, the head of a Hillary Clinton super PAC able to coordinate with the campaign, telegraphed his plans to call for the medical records this weekend here.
Politico first reported
Brock's plans, and a source with knowledge of his plans confirmed his desire to call for the records in a conversation with CNN on Saturday. Brock, who once was a Clinton antagonist, is now a vocal Clinton defender and surrogate.
The Clinton campaign, despite being able to work with Brock, publicly rejected his plan to demand Sanders' records.
"Chill out," John Podesta, Clinton's campaign manager, tweeted at Brock. "We're fighting on who would make a better President, not on who has a better Physical Fitness Test."
Brock's plans rankled Clinton's campaign aides, who, while happy to hit Sanders over policy, found the call to be distasteful.
"What the f***," a Clinton staffer mouthed when asked about the story. The staffer was granted anonymity because they were not authorized to speak on the record.
Clinton's campaign and Brock's super PAC, Correct the Record, began to coordinate in May in a move that many campaign finance experts said tested the limits of campaign laws. The groups cites a 2006 Federal Election Commission rule that states providing free content online for free -- and not producing ads -- is unable to be regulated.
There's some irony to Brock's call, as the 68-year-old Clinton has also come under scrutiny for her own health and age.
Brock's plans have already been used as a fundraising tool by the Sanders campaign.
"With just two weeks to go before the Iowa caucuses, the super PAC coordinating with Hillary Clinton's campaign is reportedly launching one of the most desperate and vile attacks imaginable: they are insinuating Bernie is too old and unhealthy to be our next president," Weaver wrote in an email to supporters.
He added, "Let me be very clear with you: Bernie is in excellent health. But this personal attack is another example of a sickness in our democracy when it is so easy for millionaires and billionaires to buy up candidates and elections."
CNN asked for Sanders' medical records in 2015 but the Sanders campaign did not respond.
Clinton released a letter from her doctor in July
, who stated that the former secretary of state was "fit to serve as President."