"I welcome the low gasoline prices," Mr. Bush said. "However, it's not going to dim my enthusiasm for making sure we diversify away from oil."
Lower gasoline prices helped bump up the president's slumping poll ratings in recent weeks, but with congressional and statehouse elections nearing in November, a sexually tainted e-mail scandal involving a Florida Republican congressman's messages to a teenage page has tarred other Republicans in the eyes of many middle-of-the-road voters.
Mr. Bush spoke at a conference en route to a fundraiser in Chicago with House Speaker Dennis Hastert to help two fellow Illinois Republicans in tough races.
The president has been backing Hastert as he fends off calls for him to resign over his handling of the congressional page scandal. Democrats claim Hastert and his staff knew of the e-mail scandal for months and did nothing about it until it was reported by ABC News.
The president on Wednesday called Hastert "very credible" and last week, a "father, teacher and coach who cares about the children of this country."
The political event in Chicago to benefit David McSweeney and Peter Roskam, two candidates for Congress, marks the first time the president has publicly appeared with Hastert since former Florida Rep. Mark Foley resigned in disgrace over sexually explicit messages he sent to teenage male pages.
Hastert insists he was not aware that the Florida congressman was sending the messages until Foley resigned two weeks ago. With less than a month to the Nov. 7 election, the White House is doing its best to prop up the speaker. White House press secretary Tony Snow plans to appear at a fundraiser with Hastert on Saturday.
Democrats need to gain 15 seats to take control of the House of Representatives and six to take power in the Senate. All 435 House seats are up for election, as are 33 of the 100 Senate seats.
In St. Louis, Mr. Bush spoke to a conference of hundreds of businessmen and women, scientists and government officials, including Energy Secretary Samuel Bodman and Agriculture Secretary Mike Johanns, who are discussing ways to fast-track the commercialization of renewable energies.
Echoing his State of the Union message that America must end its addiction to foreign oil, Mr. Bush said that by providing new sources of energy to the market, the United States can decrease overall dependence on resources abroad and power the U.S. economy with clean energy produced in the United States.
Energy is a topic that transcends the top two issues in this year's election: the economy and national security.
"We get oil from some countries that don't particularly care for us," he said.
During Mr. Bush's speech, a woman in the crowd stood up and started chanting, "Out of Iraq now" and "Our troops are not renewable." Bush did not recognize her, but continued speaking as the crowd applauded him.
Event officials pulled her out of the audience by her jacket sleeve, and she shouted louder and louder with her fist in the air as she was escorted out of the room. "What are you doing? You're killing us!" she shouted at the president, as he continued with his speech.
The high costs of oil and gas have given new momentum to the push to develop alternative fuels and alternative energy sources. The efforts are especially visible in America's heartland, where a boom in ethanol is expanding.
Six years ago, there were 54 ethanol plants in operation, Johanns says. Today, those numbers have doubled to more than 100 plants, and an additional 44 plants are under construction.
Ethanol, however, is far from a cure-all for the nation's energy problems, according to various studies. It is not as environmentally friendly as some supporters claim and would supply only 12 percent of U.S. motoring fuel — even if every acre of corn were used.
Rep. Edward J. Markey, a senior Democratic member of both the House Energy and Commerce and Resource committees, said that that while biofuels have great promise, they are only part of the solution to the problem of America's dependence on imported oil.
"Unless we mandate stronger fuel economy standards, biofuels by themselves will not be effective in helping us curb America's dependence on imported oil from the Middle East," Markey said. "Unfortunately, the president again failed to announce any new initiatives to improve motor vehicle fuel efficiency standards today."