For weeks, pressure has been mounting in Congress to approve more domestic oil drilling, but House Speaker Nancy Pelosi has held the line, using her power to block a vote on offshore drilling.

President Bush has made almost daily calls for Democratic leaders to take action. House GOP leaders, citing a new poll showing that a slim majority of Californians now favor offshore drilling, issued a release Thursday saying "even (Pelosi's) own California neighbors oppose her efforts to block new drilling far off American coasts." GOP lawmakers are so disgruntled they're urging Bush to deny Congress its August break by calling a special session on energy.

Some Democrats wary

Even some Democrats are getting antsy, fearing the party's stance could hurt them in the fall elections. But Pelosi, who has opposed offshore drilling throughout her two decades in Congress, insists opening new areas to drilling won't lower gas prices in the short term. She believes a vote would only help the GOP blame Democrats for high gas prices.

"I will not ... give the administration an excuse for its failure," Pelosi said at an end-of-session roundtable interview Thursday.

Republicans have put a bull's-eye on the federal moratorium on coastal drilling, which has kept most of the East and West coasts off limits to new oil rigs since 1982. Bush announced earlier this month that he would lift the presidential moratorium on drilling, and the GOP is now seeking to lift the congressional ban.

Pelosi drew derision from her critics for telling the Web site Politico this week that she was blocking a vote on offshore drilling because "I'm trying to save the planet." But she elaborated on that theme Thursday, saying she sees energy independence and fighting global warming as "my flagship issue." She said she will use her power to resist a policy that could increase the country's oil dependency.

"I'm not going to be diverted for a political tactic from a course of action that has a big-picture view - a vision about an energy-independent future that reduces our dependence on fossil fuels ... and focuses on those renewables that are protective of the environment," she said.

Republicans are quietly gleeful at Pelosi's tactics, which have only breathed more life into an issue the GOP is clinging to as a lifeline in an otherwise grim year for the party. Some House Republicans said Thursday that they will ask Bush to order a special session of Congress in August if lawmakers adjourn this week, as expected, without voting on drilling.

While a special session is unlikely, House Minority Leader John Boehner, R-Ohio, made clear that his party plans to use the issue as a bludgeon against Democrats throughout the five-week August recess.

"A solid majority of Americans want us to have more drilling for more American-made energy, and they aren't going to take no for an answer," Boehner said Thursday. "Speaker Pelosi, Senators (Harry) Reid and (Barack) Obama are defying the will of the American people, and they're doing so at their own risk."

Some Democrats have already started to shift their views. Rep. Tim Holden, D-Pa., who voted two years ago against drilling in the Arctic National Wildlife Refuge and for a federal ban on offshore drilling, told a hometown paper last weekend he now wants to "drill everywhere."

A new CNN/Opinion Research poll released this week found that 69 percent of Americans favor more offshore drilling, while 30 percent oppose it. But the poll found the public was split over whether more coastal drilling would lower gas prices, with 51 percent saying yes and 49 percent saying no.

But the poll's more interesting finding was about who Americans blame for $4-a-gallon gas prices: About two-thirds said oil companies and foreign countries that produce energy were the major causes. Just over half blamed the Bush administration, the war in Iraq and the moratorium on offshore drilling. But only about 1 in 3 - 31 percent - blamed Democrats in Congress for high gas prices.

A GOP opening in the fall?

"Republicans feel like they have an opening because of the gas price issue (to push for) domestic drilling, but we haven't seen any empirical evidence or tangible evidence that it's hurting Democrats," said Nathan Gonzales, political editor of the nonpartisan Rothenberg Report, which tracks House and Senate races.

"Maybe this fall the issue will develop into a Republican advantage, but I don't see that we're there yet," he said. "It's a battle of messages between the two parties more than an anvil around the necks of Democrats."

Pelosi has been holding votes on measures aimed at addressing gas prices, such as legislation to crack down on speculators in energy commodity markets and a measure to force Bush to release oil from the Strategic Petroleum Reserve. But here's the catch: The bills have won majority support, but failed to get the two-thirds backing needed to pass under special rules Pelosi has used to keep Republicans from offering a drilling measure on the House floor. Democratic leaders fear such a measure might draw enough support to pass.

The issue is likely to heat up again this fall. Republicans are debating whether to shut down the federal government - by blocking a continuing resolution to keep the government funded beyond Sept. 30 - if Democrats don't allow a vote on offshore drilling.