Jennifer Rubin has a good suggestion for McCain:

But chances are that there will be an even larger Democratic Congressional majority come next year. One consequence of this very safe projection might be that McCain will start running on that old crowd-pleaser, divided government. The prospect of a large Democratic Congressional majority unchecked by the power of the veto pen and free to pass all types of bills (from tax increases to abolishing secret ballot union elections to immigration reform devoid of border control measures) might make voters think twice about giving Democrats both ends of Pennsylvania Avenue. And Congress currently has an approval rating even worse President Bush’s. So why not run against the Democratic Congress?

With a Democratic-controlled Congress now trading above 90 percent at Intrade, both candidates will need to answer where they stand on the priorities of the Democratic leadership of Congress (such as their planned bridge to the 1930s). An added benefit for McCain is that this will help shift the context of the election, so it is no longer primarily a referendum on 8 years of President Bush, but also on the plans of Harry Reid and Nancy Pelosi.

And there's little doubt that Barack Obama is more attractive by himself than as the last barrier to enactment of the liberal Congressional agenda.