Democratic players are worried that Hillary Clinton ally David Brock could be hurting her image and hampering her chances of winning the presidency.

Concerns about the political operative's comments, particularly some of his attacks on opponent Bernie Sanders, stretch all the way to the top of Clinton's political machinery.

After news reports emerged that Brock was going to raise the issue of Sanders not having released his health records, Clinton campaign chair John Podesta shot off a tweet on Jan. 17 to Brock: "Chill out. We're fighting on who would make a better President, not on who has a better Physical Fitness Test."

Unless a major controversy develops, Brock will remain one of Clinton's key allies in 2016. He has plenty of high-profile, defenders, and even more super-PAC donor.

Clinton donor and Ballard Spahr Kenneth Jarin offered unsolicited praise for Brock, saying he was an essential countervailing force against brutal attacks on Clinton.

"I think that the Sen. Sanders campaign is bringing up negative arguments, many of which I don't think are accurate," Jarin said. "I think David Brock can shed some light on some aspects of Sen. Sanders that will be good for voters to know."