Over 90% of Sanders supporters will back Hillary Clinton, says Gov. Rendell

We'll get over 90 percent of Sanders supporters: Ed Rendell

Bernie-or-bust crowds have demonstrated outside the Democratic National Convention and booed on the floor of the Wells Fargo Center in Philadelphia, but former Pennsylvania Gov. Ed Rendell said history shows most Sanders supporters will fall in line.

"Will we get 100 percent of the Sanders supporters? No. But I remember when we left Denver in 2008, only 60 percent of Hillary supporters said they would vote for Barack Obama," the Democrat told CNBC's "Squawk Box" on Tuesday.

Independent polls taken before and after the August 2008 convention in Denver, Colorado, generally support that claim.

Two June 2008 polls cited by fact-checking website Politifact showed roughly 60 percent of Hillary Clinton's backers said they would vote for Obama in November.

A Gallup Poll taken after the convention said 81 percent of Clinton supporters planned to cast their ballot for Obama, up from 70 percent just prior to the event.

Rendell recalled Clinton campaigned vigorously for Obama throughout the fall, and the vast majority of her supporters voted for him.

Similarly, he noted, Sen. Bernie Sanders offered a full-throated endorsement of Clinton on Monday at this year's convention.

"I think we'll get over 90 percent of the Sanders supporters," Rendell said.