WASHINGTON — With his support among blue-collar white voters far weaker than among white-collar independents, President Obama is charting an alternative course to re-election should he be unable to win Ohio and other industrial states traditionally essential to Democratic presidential victories.

Without conceding ground anywhere, Mr. Obama is fighting hard for Southern and Rocky Mountain states he won in 2008, and some he did not, in calculating how to assemble the necessary 270 electoral votes. He is seeking to prove that those victories on formerly Republican turf were not flukes but the start of a trend that will make Democrats competitive there for years.

“There are a lot of ways for us to get to 270, and it’s not just the traditional map,” said David Axelrod, Mr. Obama’s chief strategist. “That’s why we’re laying the groundwork across the country to compete on the widest possible playing field next year.”

While Mr. Obama’s approval ratings have slid across the board as unemployment remains high, what buoys Democrats are the changing demographics of formerly Republican states like Colorado, where Democrats won a close Senate race in 2010, as well as Virginia and North Carolina.