The reversal is the second refinement in Obama's energy policy. Last week, he said that he would reluctantly consider accepting some offshore oil drilling. Obama had previously said he opposed such drilling, which is strongly backed by rival John McCain, who has urged that states be allowed to decide whether to drill.
Obama is scheduled to campaign this week on energy and economic issues in the battleground Midwest. McCain campaigned in Pennsylvania, where he called on Congress to return from vacation to deal with energy issues. Later, McCain travels to South Dakota.
As part of the Obama campaign's focus on energy, it released a new advertisement criticizing McCain's energy policies.
In his speech in Lansing, Obama, who celebrates his 47th birthday today, tipped his hat to McCain, quoting the Arizona Republican: "Our dangerous dependence on foreign oil has been 30 years in the making and was caused by the failure of politicians in Washington to think long-term about the future of the country," Obama said.
"What Sen. McCain neglected to mention was that during those 30 years, he was in Washington for 26 of them," Obama said.
Obama's plan would release light oil from the emergency oil stockpile and replace it later with heavier crude. Light crude oil is easier to refine into gasoline than heavier oil. In 2000, President Clinton used a similar tactic to make oil available at a time of rising oil prices.
The Obama plan is similar to efforts by congressional Democrats and is opposed by Republicans and President Bush.
House Speaker Nancy Pelosi (D-Ca.) for weeks has called on Bush to withdraw oil from the government reserve, and Sen. Jeff Bingaman (D-N.M.), chairman of the Senate Energy and Natural Resources Committee, has tried to get agreement on legislation that would require the release of 70 million barrels of oil from the government stockpile.
The McCain campaign lost no time in criticizing Obama.
"Tapping the strategic oil reserve is not a substitute for a real plan to increase supply through additional drilling and nuclear power," said campaign spokesman Tucker Bounds in a statement e-mailed to reporters.
"The strategic oil reserve exists for America's national security strategy -- not Barack Obama's election strategy. The last release of oil from the strategic reserve came in response to Hurricane Katrina, but the only crisis that has developed since Barack Obama last rejected this idea two months ago is a slide in his poll numbers," Bounds said.
Recent polls show that McCain has gained some traction on the energy issue. For example, the latest Quinnipiac University poll for the Wall Street Journal and washingtonpost.com shows that Obama tops McCain 46% to 42% compared with a previous lead of 48% to 42%.
Energy issues are the leading concern -- more important in most polls than the war in Iraq -- and voters say they support offshore oil drilling. Other polls show similar results in the West and Southwest, also key electoral battlegrounds.
In its new advertisement, the Obama campaign attacks McCain's relationship with the oil industry.
"After one president in the pocket of big oil, we can't afford another," says the ad, referring to President Bush's previous work in the oil industry.
The new Obama ad also again calls for a windfall profits tax on oil companies and a $1,000 energy rebate for families.
"Barack Obama's latest attack ads shows his celebrity is matched only by his hypocrisy," said McCain spokesman Bounds. "After all it was Sen. Obama, not John McCain, who voted for the Bush-Cheney energy bill that was a sweetheart deal for oil companies. Also not mentioned is the $400,000 from big oil contributors that Barack Obama has already pocketed in this election."
In his speech, Obama noted that there was a bipartisan compromise on energy in the works.