In earlier elections, Republican voters often turned to the most experienced candidate in their camp, a phenomenon known as “next in line.” Not this time: Of the five names on the list, none has run for president before, and only one, Bush, was a nationally-known figure five years ago. The average age of the top four — Rubio, Paul, Ryan and Christie — is 46. And Ryan doesn’t seem to get many extra points for serving as his party’s vice presidential nominee in 2012.

“It looks as if Republicans are looking for a generational change,” noted Scott Reed, who managed Bob Dole’s 1996 presidential campaign. If the Democrats nominate Clinton (who will turn 69 in 2016) or Vice President Joe Biden (who will turn 74), the GOP will have youth on its side — at least on the ticket.

But the apparent front-runners are all solidly conservative. Taken together, Rubio, Ryan and Paul win support from about half of the Republican electorate; Christie and Bush, the relative moderates, only about one-quarter.

“There’s no such thing as a moderate base in the Republican primary,” notes John Brabender, who managed Rick Santorum’s second-place finish in the 2012 GOP primary campaign. “And the voters who show up for the primary are often more conservative than the ones these polls are sampling.”