Barone: Republicans hold the heartland, Democrats the coasts

The map of the Senate races shows Republicans leading over almost all the landmass of America. Democrats are ahead in the three West Coast states and Hawaii (though not by much in California and Washington) and by 1 point in Nevada. They're also ahead in four states along the Atlantic Coast -- Maryland, Delaware, New York, Connecticut -- plus Vermont.

Republicans lead in all the other Senate races, from Philadelphia to Phoenix and Boca Raton to Boise. True, their candidate leads by only 1 point in Barack Obama's home state of Illinois. And they've got narrow leads in some mountain states (West Virginia, Colorado, Kentucky).

The map of governors' races is not much different. Democrats lead in New York, all the New England states except Maine, plus Maryland. They lead in Arkansas, where they've got a popular one-term incumbent, and in Colorado, where the party's nominee has severe resume flaws and former Republican Rep. Tom Tancredo is running as an independent. Democrats lead in Hawaii and Minnesota, normally Democratic states where Republicans have held the governorship for the last two years.

Two other big states have close races: In California, Republican Meg Whitman barely leads septuagenarian Democrat Jerry Brown, and in Florida, the race is tied.

But overall, Republicans are doing very well indeed, with statistically significant leads in every other state with a governor contest this year.

It would be more difficult to draw a map showing the party margins in the 435 House districts. For one thing, there are no publicly available polls in many districts. But if you could draw such a map, I think you'd see Democrats holding onto districts dominated by their core constituencies (blacks, Hispanics and the affluent voters Joel Kotkin calls gentry liberals) and struggling just about everywhere else, from factory towns to high-income suburbs.

Taken together, all these maps show a Democratic Party shrinking back to its bicoastal base and a Republican Party spreading to take in most of the vast expanse of the continent.