By Steve Holland

FRESNO, California (Reuters) - Republican John McCain said on Monday if elected president he would challenge American experts to develop a futuristic battery to power cars and win a $300 million prize.


McCain, a week after taking heat from Democrats for reversing his stance on offshore oil drilling after long opposing it, sought to portray himself as a forward-looking leader on solving America's energy crisis.

With Americans reeling from record-high $4-a-gallon gasoline during the prime summer driving season, both McCain and his Democratic opponent in the November election, Barack Obama, are pressing their proposals for tackling energy problems that are dragging down the U.S. economy.

McCain noted that Brazil has largely weaned itself from oil imports by converting most new cars to flex-fuel capacity that use alcohol-based fuels. Brazil went from 5 percent to 70 percent of flex-fuel new cars in three years, he said.

"Whether it takes a meeting with automakers during my first month in office, or my signature on an act of Congress, we will meet the goal of a swift conversion of American vehicles away from oil," McCain told a town hall meeting in Fresno, in rural central California.

The Arizona senator, 71, who would be the oldest person elected to a first presidential term, finds himself behind Obama in polls but not by a wide margin.

But in a worry for him, a USA Today/Gallup poll published on Monday said voters are most concerned about energy and the economy and they prefer Obama by a double-digit margin on each.

McCain said he would issue a Clean Car Challenge to U.S. automakers.

"For every automaker who can sell a zero-emissions car, we will commit a $5,000 dollar tax credit for each and every customer who buys that car. For other vehicles, whatever type they may be, the lower the carbon emissions, the higher the tax credit," he said.

And he offered a big reward for whoever comes up with a technological breakthrough: "A $300 million prize for the development of a battery package that has the size, capacity, cost and power to leapfrog the commercially available plug-in hybrids or electric cars."

McCain, who has taken steps to distance himself from unpopular President George W. Bush, also seemed to take a dim view of efforts by Bush and others to persuade OPEC nations to lower the price of crude.

"Some in Washington seem to think that we can still persuade OPEC to lower prices -- as if reason or cajolery had never been tried before. Others have even suggested suing OPEC -- as if we can litigate our way to energy security," he said.

The Obama campaign held a conference call with reporters to respond to McCain's energy speech and reacted with skepticism.

Obama economic adviser Jason Furman said over his long career in the U.S. Congress McCain "had the chance to make a difference for energy security and America's families."

"And he consistently not only didn't make a different but has stood in the way of the people like Senator Obama who have been trying to improve our energy security," Furman said.

(Additional reporting by Deborah Charles and Jeff Mason; Editing by David Wiessler)

© Copyright 2008 Reuters.

Photo:
Presumptive Republican presidential candidate US Senator John McCain pauses while delivering a speech to the Economic Club of Canada in Ottawa June 20, 2008. REUTERS/Chris Wattie