The overwhelming majority of funds donated to a super PAC supporting Sen. Elizabeth Warren’s (D-Mass.) presidential bid came from a sole donor, according to new Federal Election Commission filings. 

Karla Jurvetson, a wealthy doctor in California, donated an eye-popping $14.6 million to Persist PAC, a group that sought to revive Warren’s faltering campaign in February.

The funds from Jurvetson made up the lion’s share of the roughly $15.1 million the super PAC raised last month in its efforts to boost Warren, who, prior to the group’s formation, had stumbled after third- and fourth-place finishes in Iowa and New Hampshire.