Political author Hytner: Bill Clinton back in WH mix if Hillary wins 2016

Former President Clinton can't get back into the Oval Office, but it doesn't mean his days of calling the shots in U.S. politics are done.

If Hillary ClintonHillary Rodham Clinton5 challenges for new DNC chairman Tom Perez New DNC chair Perez will attend Trump's speech as former rival's guest Dem questions FBI chief's commitment to Russia review MORE runs and is elected president in 2016, the 42nd president could make some of the most powerful decisions for her as her top adviser, according to author Richard Hytner. Hytner recently wrote Consiglieri: Leading from the Shadows, which focuses on past and present figures who make crucial political decisions without being in the limelight.

"If H.R.C. runs, and if she wins, I think the critical adviser, the person who will have to learn how to be the spouse and adviser very much behind the scenes is Bill ClintonBill ClintonFinally, an immigration reform bill that tackles family migration 5 ways politics could steal the show at Oscars Clinton: Dems will be 'strong, unified' with Perez MORE," Hytner said.

The former first lady and secretary of State told ABC News in a recent interview that she will decide if she's running at the end of the year.

For the Obama administration, Hytner said Valerie Jarrett ranks high on the list of those who currently lead in the shadows, and suggested that President Obama holds the highest trust in her as an adviser.