Washington (CNN) -- There is no argument the Republican presidential field has breadth. 

From Mitt Romney, the former Republican governor of liberal Massachusetts, who needs to convince primary doubters of his core conservatism to Texas Rep. Ron Paul, sometimes called "the intellectual godfather" of the Tea Party, who needs to convince doubters that in his third run at the job he is more than a conversation-mover. 

It's largely a field of formers -- not a contemporary marquee name or a perfect fit in the bunch: 

Former House Speaker Newt Gingrich -- a conservative big-idea guy, who often careens off-message and carries some personal baggage. He might be carrying his own actual baggage now since almost his entire senior campaign staff has bolted. 

An inside look at Monday's CNN debate 

Former Minnesota Gov. Tim Pawlenty -- like Romney, he has chief executive credibility, having maneuvered his way through two terms in one of the bluest states in the country, but he'll have to defend some of that record to a conservative base and work on upping his campaign skills to the national level. 

Former Pennsylvania Sen. Rick Santorum -- a favorite of social conservatives whose first pressing problem is convincing people he has a shot at powerhouse Team Obama. 

And the former CEO of Godfather's Pizza Herman Cain, a conservative radio host. Dismissed by Republican stalwarts as entertainment, he has nonetheless found some poll traction. 

Profiles of the seven GOP contenders 

There is some question about depth -- almost 40% of Republicans say they're not satisfied with the field. Critics have called it weak but a top Republican strategist thinks it's more like wide-open, American style. 
what is he?
Mitt Romney, the former Republican