President Obama stood in a red-dirt field before acres of stacked pipeline pieces on Thursday to illustrate his support for expedited construction of the southern half of the controversial Keystone XL oil pipeline. But his public declaration of support for the project has pleased neither the industry and its Republican supporters nor environmentalists. Mr. Obama’s appearance here near the oil town of Cushing, Okla., known in the industry as the nation’s pipeline crossroads, was intended to blunt months of criticism from Republicans in Congress and on the presidential campaign trail of his decision in January to reject for now construction of the pipeline’s northern leg from Alberta, in Canada, to Cushing. The attacks have gained resonance as gasoline prices have spiked, and Congressional Republicans have sought to force action. “Unfortunately, Congress decided they wanted their own timeline,” Mr. Obama told an invited audience of about 200 people. “We’ve told the company that we’re happy to review future permits. And today, we’re making this new pipeline from Cushing to the gulf a priority.” “The fact is, my administration has approved dozens of new oil and gas pipelines over the last three years — including one from Canada,” he added. “And as long as I’m president, we’re going to keep on encouraging oil development and infrastructure, and we’re going to do it in a way that protects the health and safety of the American people.” But environmentalists nationwide have rallied to oppose the entire Canada-to-Gulf Coast pipeline because its owner, TransCanada, wants to transport what environmental groups consider dirty oil from the tar sands of Alberta. The groups say such oil would hasten climate change, threaten spills and pollute air, water and wildlife. While the southern leg is planned to relieve a bottleneck of oil from the Plains states awaiting shipment to gulf refineries and vessels, opponents say the pipeline ultimately would be used to transport tar sands oil, much of it for export globally, if TransCanada eventually secures approval from the United States to build the northern half. “In expediting the southern portion of Keystone XL, President Obama is trying to have it both ways,” said Becky Bond, political director of Credo Action, part of a coalition of environmental groups that issued a joint statement of opposition. “The president needs to prove that his initial rejection of Keystone XL wasn’t simply a ploy to placate the environmental voters who dared to hold him to his own rhetoric about the need for real leadership on climate and our fossil fuel dependence,” she said. The administration, and specifically the State Department, must approve a permit for the pipeline to cross the border between Canada and the United States, a process that requires exhaustive environmental studies. Mr. Obama rejected TransCanada’s initial path through the Ogallala Aquifer in Nebraska — a route opposed by many Nebraskans as well — but the company plans to resubmit its application for an alternate route. As gasoline prices have risen to the $4-a-gallon mark nationwide, Republicans have stepped up their attacks against Mr. Obama’s decision, claiming it stands in the way of lower pump prices and thousands of construction jobs. The administration counters that the job figures are inflated, and that oil from the pipeline would not reach markets anytime soon. Even before Mr. Obama reached Oklahoma on the final day of a two-day energy tour, Republicans were deriding the Oklahoma stop as a publicity stunt since the only federal permits that the Cushing-to-gulf pipeline needs are ones typically handled by government agency employees — not the president. “After rejecting and personally lobbying against Keystone XL and thousands of new jobs, the president plans to tout that he’s now interjecting himself on behalf of a routine permit that is normally handled by bureaucrats,” aides to the House speaker, John A. Boehner, Republican of Ohio, wrote in a blog post on Thursday. A Boehner spokesman, Brendan Buck, added, “This is like the governor holding a press conference to renew my driver’s license.” With his four-state swing, Mr. Obama is promoting what he calls his “all of the above” energy policy to reduce both consumption and dependence on foreign oil by government support for clean-energy alternatives as well as for domestic oil and natural gas and by increased fuel-efficiency standards for vehicles. Mr. Obama contrasts that agenda with what he characterizes as Republicans’ drilling-only agenda. Seeking to turn the tables on his Republican critics, Mr. Obama, by stops like the one in Oklahoma, has tried to show that he is not hostile to oil and gas production, even as he charges that Republicans are hostile to clean-energy incentives. Instead of a drilling-only agenda, he said, an “all-of-the-above strategy” means encouraging with tax and spending incentives more biofuels, fuel-efficient cars, solar power and wind power — “which, by the way, has nearly tripled here in Oklahoma over the past three years, in part because of some of our policies.” Mr. Obama on Wednesday stopped at the nation’s largest solar-power plant, in Nevada, and viewed oil rigs on government-leased lands in New Mexico before reaching Oklahoma. In Ohio he will tour Ohio State University’s Center for Automotive Research in Columbus. While his trip to Ohio, an election battleground state, is his second in two weeks, he noted in Ripley that he had not been in Oklahoma since the 2008 presidential campaign. In the general election, Republican-red Oklahoma opposed Mr. Obama by a higher percentage than any other state — 66 percent voted for his Republican opponent, Senator John McCain.