Ickes told the Sunday Times that he's on board with the Ready for Hillary super-PAC, which was launched earlier, independent of Clinton, to begin to build an operation for her potential run.
He also said he's been in touch with Clinton donors who want her to run.
"These are people I know who have told me over the years that they and a lot of other people want her to run. They don't have any idea what she's going to do, but if she runs they want to be ready to give whatever assistance they can," he said.
Ickes, who served as then-President Bill Clinton's deputy chief of staff, joins Democratic strategist James Carville in backing the new super-PAC. Carville recently lent his name to a fundraising pitch sent out by the group.
Clinton sparked renewed speculation surrounding her political future with her reemergence on the public stage this week. She gave two public addresses on womens' rights in Washington and New York, and news broke of a book she's writing about her time at State.
But even as her supporters line up to join her presumed campaign, she's remained quiet about her actual plans. Clinton previously said that after retiring in late January she planned to take some time to be a private citizen and recuperate after a busy stint as secretary of State.
“I just want to sleep and exercise and travel for fun. And relax," she said then.