President Obama's re-election campaign is joining an escalating air war over gas prices and oil subsidies with a new TV ad in several states attacking Mitt Romney as a defender of "Big Oil."

The 30-second spot, airing in Colorado, Florida, Iowa, Nevada, Ohio and Virginia, portrays President Obama as under attack by wealthy oil companies and their allies who feel threatened by his calls to eliminate taxpayer subsidies and invest in new energy sources.

View the ad HERE.

"In all these fights, Mitt Romney's stood with Big Oil - for their tax breaks, attacking higher mileage standards and renewables," the narrator says.

The ad also reacts to a $3.6 million  ad campaign launched last week by the American Energy Alliance - a nonprofit group with Republican ties - that is sharply critical of the president for gas prices and his handling of the Keystone XL pipeline and the failed solar start-up Solyndra.

"When you see this ad," the Obama ad says in response, "remember who paid for it.  And what they want."

The American Energy Alliance is reportedly funded in part by billionaire oil magnates Charles and David Koch, though the group does not have to disclose its donors or say what they contributed.

"It's no surprise President Obama is spending his soon-to-be $1 billion war chest to attack Mitt Romney and deflect blame for his failure to control gas prices," said Romney spokeswoman Andrea Saul.

Republican National Committee spokeswoman Kirsten Kukowski said the ad suggests Obama is "panicked" about the impact high gas prices may have on his re-election.

"Instead of implementing solutions, the president is once again trying to mislead voters with a negative attack ad in an attempt to get re-elected," Kukowski said. "So much for the hope and change the president promised."

Obama's new ad - called "Remember" - is his third of the 2012 election campaign and second on the topic of energy, responding directly to attacks by outside political groups.

Obama's first major TV ad buy came in January in direct response to attacks by the group Americans for Prosperity, which also has ties to the Koch brothers.