I’ve wondered from time to time whether John McCain would make this pitch, and now George Stephanopolous reports that the decision has been made.  The McCain campaign will use three themes in the final week, and one of them will be to warn voters against allowing a Democratic Congress free rein with a Democratic President:

Democrats “United”: The McCain campaign will argue the nation needs a McCain administration to check a Congress led by Democrats House Speaker Nancy Pelosi and Senate Majority Leader Harry Reid. Already Republican are running television ads in places like North Carolina where Republican Sen. Elizabeth Dole is fighting against Democratic challenger, state Sen. Kay Hagan to hold onto her seat.

Watch for Republicans to raise the specter of a Obama-Pelosi-Reid administration that is not going to be checked by a Republican Congress.

This makes a powerful argument, but one that assumes that Republicans won’t bounce back in Congress in this election.  A couple of months ago, their prospects looked brighter while Pelosi refused to return to Capitol Hill from her book tour as gas prices skyrocketed.  The prospect for a majority in the House has dimmed since then, thanks to the financial collapse and the sharp decrease in the price of oil.

With that possibility diminishing, it gives McCain an opportunity he might otherwise eschew.  He can argue that a Congress run by partisans like Reid and Pelosi would run amok without a Republican in the White House — and fortunately he can use recent history as a guide.  The Pelosi-Reid Congress has done little but hold hearings in the last two years, mostly because they can’t get their radical agenda past the Bush administration.

They have also garnered a lower approval rating than George Bush, which gives McCain another reason to use this theme in the final week.  Barack Obama has tied McCain to Bush, and now McCain can tie Obama to Reid and Pelosi.  McCain began doing this a couple of months ago, noting that Obama hardly ever deviates from his party leadership (97% loyalty).  Now he can leverage the unpopularity of Congress under Democratic leadership by attaching it to Obama more explicitly.

The other two themes?  Pretty obvious: Joe the Plumber and Joe the Drip’s warning about Obama provoking international crises.  When your opponent gives you those kinds of gifts, it’s downright rude not to use them.