Senior advisers to Hillary Clinton feared that Sen. Elizabeth Warren (D., Mass.) would back primary opponent Bernie Sanders if the Democratic presidential nominee failed to forcefully oppose Wall Street banking, according to emails published by WikiLeaks on Monday.

Clinton aides expressed concern that a weak stance against big banks could "antagonize and activate" Warren and potentially drive her to support Sanders, a self-declared socialist, the Hill reported.

WikiLeaks released 2,000 documents Monday from the email account of Clinton’s campaign chairman, John Podesta. The latest email dump came three days after the U.S. government formally accused the Russian government of hacking into political networks to influence the 2016 election.

One of the newly leaked email exchanges detailed advisers mulling over whether Clinton’s economic policy to reform Wall Street should include the revival of the now-repealed Glass-Steagall Act, which separated investment and commercial banking activities.

Those politically left of Clinton, including Warren and Sanders, have called for the return of the law to again wholly isolate Wall Street trading from traditional banking.

Though the Clinton campaign ultimately decided against including a call to reinstate Glass-Steagall in her policy proposal, her top advisers discussed the former law considerably.

"I am still worried that we will antagonize and activate Elizabeth Warren by opposing a new Glass Steagall. I worry about defending the banks in the debate," Mandy Grunwald, one of Clinton’s longtime advisers, wrote in an email. "I worry about Elizabeth deciding to endorse Bernie."

Warren withheld an endorsement until Clinton had effectively clinched the Democratic nomination.