From FoxNews:

Conservatives - Mike Huckabee 32%, John McCain 26%, Mitt Romney 19%, Fred Thompson 17%

Independents – John McCain 37%, Mike Huckabee 23%, Ron Paul 15%, Mitt Romney 14%

Evangelicals – Mike Huckabee 41%, John McCain 27%, Fred Thompson 14%, Mitt Romney 11%

Veterans – John McCain 36%, Mike Huckabee 25%, Mitt Romney 20%, Fred Thompson 13%

As far as the three most important issues to voters: McCain and Huckabee are tied on the economy, Huckabee is leading on immigration and McCain is winning on Iraq.