Some of the 18% that blame Obama are potential GOP votes. Eisenhower called them "right thinking democrats."
The GOP has lost the popular vote for President, 5 of the last 6 times. The only conservative President in 80 years was Reagan and he would not meet the criteria for "conservative" in many circles. (Nor would Goldwater).
The center-right needs a candidate they can unify with, or go down to another defeat. Governors with positive records instead of Senators. Governors that have won elections in democrat states-Walker, Christie, Sandoval, Martinez etc.