WASHINGTON -- Soaring gasoline prices are threatening to undercut President Barack Obama's re-election prospects and offering Republicans an easy target. With prices pushing $4 a gallon and threatening to go even higher, Obama sought Thursday to confront rising public anxiety and strike back at his GOP critics.

"Only in politics do people root for bad news, do they greet bad news so enthusiastically," Obama said of Republicans. "You pay more; they're licking their chops."

Obama said dismissively that all the Republicans can talk about is more drilling -- "a bumper sticker ... a strategy to get politicians through an election" -- when the nation's energy challenges demand much more. In a speech in Miami, he promoted the expansion of domestic oil and gas exploration but also the development of new forms of energy.

Economists say there's not much a president of either party can do about gasoline prices. Certainly not in the short term. But a new Associated Press-GfK poll says seven in 10 find the issue deeply important.

"Right now, we're experiencing yet another painful reminder of why developing new energy is so critical to our future," the president said. At an average of $3.58 a gallon, prices are already up 25 cents since Jan. 1, and experts say they could reach a record $4.25 a gallon by Memorial Day. Those higher prices could hurt consumer spending and unravel improvements in the economy.

While motorists already are starting to complain, many economists see the $4-a-gallon mark as a breaking point above which the economy starts to suffer real pain. Analysts estimate that every one-cent increase is roughly a $1.4 billon drain on the economy.

Obama's rivals have stepped up attacks on his energy policies. And they're full of promises. "I've developed a program for American energy so no future president will ever bow to a Saudi king again, and so every American can look forward to $2.50-a-gallon gasoline," former House Speaker Newt Gingrich said in the Wednesday GOP debate in Mesa, Ariz. His strategy: "Drill Here, Drill Now."

At the same event, former Sen. Rick Santorum of Pennsylvania asserted that "we have a lot of troubles around the world, as you see the Middle East in flames and what's going on in this country with gas prices and the economy." And former Massachusetts Gov. Mitt Romney suggested that even more troubling than rising gasoline prices was Iranian President Mahmoud "Ahmadinejad with nuclear weapons."