Not when it comes to the defense of our nation.
The GOP can not be expected to fight their own President
Plenty of Repubs have fought against GWB. Thus, your argument fails.
Plenty of Repubs have gone along with GWB on social security, education etc.
Also, I do not think McCain can be trusted on the war. His Dem buddies will not allow it. McCain knows this is an issue which will force Repubs to vote for him (not me). Once he takes office he will act as he pleases and with McCain this is comnpletely unpredictable.