I agree within states like Texas but in Texas and other strongly conservative states voters want a more conservative republican on average and as important as Texas is with the economy, resources and population it will honestly have much more to do with how the people of the usual battle ground states vote. Ohio, Pennsylvania, Virginia, Florida, Missouri etc.It could be a huge difference if nominating Romney or another pale imitation Obama costs them 5% of the votes to a third party conservative candidate.
These states will more then likely determine the election next year. States like Texas aren't going to have its electoral college points go for Obama and New York and Illinois isn't going republican. Most of the battle ground states want moderate republicans not hard line conservatives. It doesn't matter if Obama only gets 20% of the vote in Texas if he wins just a few key states like we saw last election. In 08 56% of the popular vote in Texas voted republican and it will likely increase to 60%-70% next year but it won't matter if he wins key states.
Hopefully all the swing states that went Obama in 08 will wise up and vote republican NO matter who is their nominee.
If just a few states like NM, CO, MN, WI etc vote republican it will change everything. I assume at least half of these states will go back to Rep. next year and these states aren't even the closest races.