Someone off the radar, someone without “baggage”, someone who can be sold as “hip” to young (first time, low information) voters.
O’Malley?
Someone off the radar, such as Castro from Texas, the former mayor of San Antonio, now HUD secretary?
He’s young and hip and liberal.
I’ve heard that Democrats have a tendency to go for new candidates who burst onto the scene.
We can think of a few from recent history.
Jimmy Carter was unknown to most Americans as he began his quest for the 1976 Democrat nomination.
Same with Dukakis in 1988. He wasn’t a national figure at first.
Bill Clinton was not well known nationally until he ran for president in 1992.
And Obama was relatively unknown nationally when he ran for president against the universally known Hillary in the 2008 primaries.
I’ve heard lots of talk that Hillary just isn’t liberal enough or exciting enough for many Democrats. In spite of polls showing broad support, other candidates could jump into the race and deflate her support.