WASHINGTON — This year’s unusual presidential election may toss out one more assumption: the old red-blue map that shows Democrats owning the two coasts, Republicans dominating the South and interior West, and a few battleground states picking the winner.

As Sen. Barack Obama moves toward the Democratic nomination, analysts think he could be riding a wave, where a fresh face coupled with a deep desire among voters for change overwhelms traditional partisan geography, topples GOP strongholds and delivers a powerful new majority for Democrats.

Yet after being written off last summer, Sen. John McCain emerged as the Republican best positioned to hold the White House for his party in a year when nearly everything is against him: an unpopular war, soaring gas prices, sinking home values, and a Republican incumbent with poisonous approval ratings.

Analysts point to last Tuesday’s twin primaries in Oregon and Kentucky to show how McCain could beat the odds.

The same day that Obama enthralled the young, educated voters of Oregon, he was thrashed in Kentucky, losing many counties by 85 percent and 90 percent margins.

And these were Democrats. Parts of pivotal Ohio and Pennsylvania mirror or include Appalachia.

The general election will operate very differently from the Democratic primaries, where Obama held his early lead by accumulating delegates based on his share of the vote, keeping the race tight even when he lost big states like California and Ohio to Sen. Hillary Clinton. In the Electoral College, the winner of each state takes all its electoral votes. The aim is to reach 270 out of a total of 538.

“All things being equal, Obama is a decent bet to break 300, just because it’s a very good year for Democrats,” said Daron Shaw, a University of Texas professor who worked for Bush in 2000 and consulted for the Republican National Committee in 2004. Holding the blue states and winning Ohio could give him the presidency with one electoral vote to spare.

“But boy, if he loses Ohio and turns around and loses Pennsylvania,” Shaw said, “then he’s got a math problem.”