Congress is set to leave for its August recess without passing any significant legislation to address gasoline prices, as both parties hardened their positions in preparation for the fall campaigns.

Democrats seized on Exxon Mobil Corp.’s announcement Thursday of an $11.7 billion second-quarter profit — the biggest quarterly profit ever by a U.S. corporation — in a bid to regain the political initiative on energy policy.

For months, Republicans have pummeled Democrats for resisting calls to lift restrictions on oil and gas drilling off U.S. shorelines. Democrats counterattacked Thursday, with a new theme portraying GOP support for drilling as a giveaway to big oil companies.

Charles E. Schumer, D-N.Y., chairman of the Democratic Senatorial Campaign Committee (DSCC), said new ads tying Republicans in competitive races to oil companies will begin running across the country in the coming weeks. The ads will highlight targeted Republicans’ votes to preserve tax breaks for oil companies while rejecting tax incentives to encourage development of alternative energy, Schumer said.

The DSCC also has unveiled a new Web site detailing oil industry contributions and votes by Republican senators.

“I would say it took us a few days to get our sea legs,” Schumer said, conceding that the Democrats’ energy message has been muddled. “We had many different voices here, but once we congealed around big oil and alternatives — bam! The message is out. The momentum is now on our side. It changed here in a week.”

Republicans, meanwhile, showed no sign of backing down on their call to lift bans on oil and gas drilling off most of the U.S. coast and develop shale oil reserves in the West.

“Democrats’ lack of ideas on how to solve rising gas prices is deafening in our races, and our candidates’ solutions are resonating,” said Rebecca Fisher, communications director for the National Republican Senatorial Committee. “That is driving the Democrats crazy right now, so this knee-jerk response is not a surprise at all.”

The partisan tangle that has tied up the Senate was highlighted Thursday during debate on energy policy that was more theater than lawmaking.

Majority Leader Harry Reid, D-Nev., asked for unanimous consent to pass a series of bills that have been blocked by Republicans, including measures to extend tax credits for developing alternative energy (HR 6049), strip oil companies of unused leases, subject the Organization of Petroleum Exporting Countries to U.S. antitrust laws (HR 2264), bolster regulation of energy futures trading (S 3268) and require oil companies to invest a portion of their profits in alternative-energy projects (S 3044).

The move forced Republicans to object to each measure. Minority Leader Mitch McConnell, R-Ky., countered by asking for consent on Republican proposals to lift restrictions on offshore drilling, streamline permitting for nuclear power and promote development of “clean coal” technology.

Meanwhile, there was no progress Thursday on energy legislation in the House. Democratic leaders will wait until September to resume efforts to pass a bill (HR 6604) designed to curb speculation in energy markets.

The bill failed July 30 by a vote of 276-151, under an expedited procedure that required a two-thirds majority vote for passage, but leaders said they plan to bring the measure back under different floor rules that require a simple majority.

House Speaker Nancy Pelosi, D-Calif., has refused to allow an offshore drilling vote to get to the floor, but suggested to reporters Thursday that she could foresee such a vote in the context of a broader energy bill that would include a host of Democratic-sponsored initiatives that the GOP leadership and President Bush oppose.

“It could be in a bigger picture of things as all these things come together,” Pelosi said. “But I’m not going to have this big path that we’re going down sidetracked by a political ploy of the Republicans.”

After the press session, Pelosi aides issued a statement reiterating that she has no intention of bringing to the floor legislation that would allow drilling in currently protected areas.

As both parties sharpen their messages, they can point to recent polls for evidence they are gaining traction.

A CNN/Opinion Research poll released Thursday found that 51 percent of respondents blamed laws banning oil and gas drilling offshore and in wilderness areas for higher gas prices. That is good news for Republicans pursuing their drilling message.

However, the same poll found that 68 percent of respondents believe U.S. oil companies are the major cause of high gasoline prices. And the poll found that 54 percent of respondents blamed the Bush administration for high prices, while 31 percent blamed congressional Democrats.

While both parties have benefited from oil industry campaign contributions, Republicans have enjoyed a decided advantage. Since 2002, oil and gas producers’ political action committees have given $9.2 million to Republicans and $1.9 million to Democrats, according to data compiled by CQ MoneyLine.

Sherry Bebitch Jeffe, a political analyst and senior scholar at the University of Southern California, said the relentless Republican attacks on drilling have hurt Democrats, who have been slow to counter them.

“It’s interesting to me that it’s taken so long [for Democrats] to figure out how to come back on this without giving in on offshore drilling,” she said.

With Congress paralyzed on energy legislation, a bipartisan group of 10 senators, led by Democrat Kent Conrad of North Dakota and Republican Saxby Chambliss of Georgia, plans to announce on Friday a road map for action on energy legislation.

Highlights of the draft plan are expected to include proposals to intensify efforts to shift vehicles to non-petroleum-based fuels, promote conservation and energy efficiency and permit targeted domestic energy production.

The plan would open new areas in the Gulf of Mexico to energy production and also allow Virginia, the Carolinas and Georgia to allow drilling up to 50 miles off their shores.

Catharine Richert, Edward Epstein and Greg Vadala contributed to this story.