I think Romney is a Christie supporter. Northeast Governors. Christie gave the RNC keynote (which was odd, but still).
As for Scott Walker I think he's the leading conservative-establishment candidate. He's the type of guy that Republicans were searching for in 2012, when they were dealt Santorum, Gingrich, Perry, etc. He's a career politician so he should do well during the debates, his goal should be to kick out the other guys in his mold (Perry, Santorum, Huckabee, Jindal) as quickly as possible to collect their donor money and votes.