Sen. McCain, Sen. Brownback, and Rep. Hunter are conservative, and ex-Rep. Gingrich will probably run. The conservative vote will probably split among those four.
Gingrich is unlikely to get in (unless drafted which I find not likely.) Brownback has and will have virtually no conservative support because he and What-his-name, the Gov. of Arkansas, are taking on some liberal issues, just not on the the social issues, more straddling that doesn't fool anybody. McCain hasn't had any conservative support since before 2000. Hunter will get absolutely no $ except what he's able to raise strictly from grassroots people as he is not only the Democrats worst nightmare, but also the worst nightmare of the Rockefeller Republicans. One of them may survive to see Iowa. If I had to guess, I'd say it will be Hunter as he can raise enthusiasm if not $. Tancredo is another possibility, but he'll be without $ and won't be hard to paint as "mean" like the press does to Cheney.