“It’s not as cool to be an Obama supporter as it was in 2008, with the posters and all of that stuff,” he acknowledged to an intimate gathering of donors in Miami this week.

It’s a line he delivered with a chuckle, a variation on a theme that he is using with his base of supporters. But it holds an important truth for the Obama campaign: Obama is now a known quantity and he will not inspire voters this election the same way he did in the previous one.

Complicating things for Obama is what the Pew Research Center calls an “intensity gap” between Obama’s conservative opponents and the liberals who would be most likely to support him. A recent Pew survey found that 84 percent of staunch conservatives strongly disapprove of the president, but only 64 percent of solid liberals strongly approve of him.