The Republicans are putting their eggs in the presidential basket. They are in a weaker position then the Democrats in Senate and House races, but have some kind of shot at winning the presidential election. From their perspective, both Clinton and Obama have vulnerabilities.
GHWB with his signing statements, disciplined coaching and supporting national media has pushed a strong president model. This has been aided by a timid Democratic Congress. If McCain should win, we would certainly see this model continue.
Despite the Democratic lack of spine to date, if the worst were to happen, we'd have no choice but to push for a more ideological and more confrontational Congress.