President Obama reiterated his call for Congress to repeal federal subsidies to the oil industry Thursday, escalating a political skirmish with Republicans over rising gasoline prices amid evidence that much of the public remains uncertain about who is to blame.

Nearly one-quarter of Americans do not know who to hold most responsible for the spike in prices, which have shot up 47 cents per gallon over the past two months, according to a new Washington Post-Pew Research Center poll. That outpaces the 18 percent who blame the president and 14 percent who name big oil companies.

The results illustrate the high stakes for Obama as he tries to shape the public debate and rally support behind his energy policies to help insulate him from an issue that presents significant political risks in an election year. Some analysts fear that gasoline prices could shoot up another 50 cents per gallon this spring, potentially stunting consumer spending and slowing an economic recovery.

Speaking before a crowd of 1,000 at Nashua Community College in New Hampshire, Obama defended his energy policies for the second time in as many weeks, saying there were “no quick fixes” to escalating prices at the pump.

But the president insisted that lawmakers should vote in the next few weeks to repeal oil industry’s $4 billion federal subsidies, a demand he has made several times over the past three years. Ending the “industry giveaway,” Obama argued, would spur the development of alternative energy sources that could offer long-term relief from rising gas prices.

“Every time you fill up your gas tank, they’re making money,” Obama said of the gas companies. “Does anyone really think Congress should give them another $4 billion this year? Of course not. It’s outrageous. It’s inexcusable.”

He added: “Let’s put every single member of Congress on record: You can stand with oil companies, or you can stand up for the American people.”

Republicans, and some Democrats, citing findings from the nonpartisan Congressional Research Service, argue that repealing the subsidies would raise the price of gasoline by putting additional costs on the oil companies.

And Obama’s GOP presidential rivals ramped up criticism of the administration’s policies and blamed the president for the shock at the pump.

“Americans deserve a president who can deliver real energy solutions and pro-growth policies, not more empty rhetoric and broken promises,” said Andrea Saul, spokeswoman for GOP presidential candidate Mitt Romney.

The Washington Post-Pew Research Center poll shows a significant partisan split over who to blame for the price spike, with 33 percent of Republicans naming Obama compared to just 5 percent of Democrats and 20 percent of independents. The poll also shows that 11 percent of the public cites uncertainty in Iran and the Middle East as the primary factor.

But perhaps the most notable statistic is the large number of people who do not know what the cause is. When Pew Research conducted similar surveys of public attitudes over rising gas prices in 2005 and 2006, more people blamed then-President George W. Bush and fewer were undecided. That suggests an opening remains for Obama to frame the debate to his favor over the coming weeks.

In his remarks, Obama accused his critics who are calling for more domestic drilling to counter the spike in gas prices of not being honest about the increase in domestic production under his watch. Though he acknowledged that previous administrations’ energy policies have helped, Obama held up a chart showing that the nation’s dependence on foreign oil has dropped each of his three years in office.

But, he added, despite the drop, gas prices are still subject to spikes because “the amount of oil we drill at home doesn’t set the price of gas on its own. That’s because oil is bought and sold in a world market. And just like last year, the biggest thing that’s causing the price of oil to rise right now is instability in the Middle East — this time in Iran.”

Obama had already demanded that Congress repeal the oil industry subsidies on three occasions before Thursday’s request. Each time, the proposal was defeated following heavy industry lobbying.

Obama said ending the subsidies would allow for greater incentives for companies that produce alternative forms of “clean energy,” though he made a tacit reference to Solyndra, a green energy firm that went bankrupt after winning a $500 million government-backed loan from the administration.

“Some of the clean energy technologies we discover won’t pan out; some companies will fail,” Obama said. “But as long as I’m president, I will not walk away from the promise of clean energy. . . .We want to ensure a future that is not controlled by events on the other side of the world.”

Washington Post polling director Jon Cohen contributed to this report.