“Unquestionably, without going into names, a more centrist Republican candidate is tougher to campaign against,” said Rep. Steve Israel (N.Y.), who’s heading the messaging strategy for House Democrats. 

“All the polling shows us that the Republican brand is highly unpopular,” Israel added. “A Republican who’s reflecting that brand all the way on the right is easy to win against. A Republican who plays against the brand is harder to win against.” 

Behind Bush, Democrats are also wary of Wisconsin Gov. Scott Walker and Sen. Marco Rubio (Fla.), two relatively new faces who have nonetheless proven to be effective fundraisers while appealing to conservatives and independents alike. 

Rep. Raúl Grijalva (D-Ariz.) characterized both as “formidable opponents,” singling out Rubio as particularly tough “because he has no record” and “can make it up as he goes.”