Sen. Barack Obama will exchange ideas on economic competitiveness tomorrow at Carnegie Mellon University, the same stage his November rival, Sen. John S. McCain, chose to showcase his economic views earlier this spring.

The closed event follows a three-week campaign itinerary in which the Illinois senator highlighted aspects of the economy, the issue that has earned a lock on the first position in every recent poll's list of voter concerns. In recent days, the presumptive presidential candidates have sparred on the economic and environmental impact of energy issues.

Speaking in California yesterday, Mr. McCain called for increased energy efficiency by government and improvements in the national power grid. In recent days he has also called for easing restrictions on offshore oil drilling, a position for which national polls show increasing support, but one which carries special risk in battleground states such as Florida and California. Lumping it with Mr. McCain's call for a summer suspension of gas taxes and a $300 million award for battery innovation, Mr. Obama has called the proposal a gimmick.

Mr. McCain first called for the gas tax holiday in his speech on the economy on April 15 at CMU. In the address, the GOP standard-bearer also called for a cut in corporate tax rates, an end to the alternative minimum tax, and a war against pork barrel spending.

This will be Mr. Obama's first appearance in Western Pennsylvania since the April Democratic primary in which Sen. Hillary Rodham Clinton of New York soundly defeated him. Mr. Obama mended his fences with the state's political establishment, which mostly backed Mrs. Clinton, at a fund-raising event earlier this month in Philadelphia.

The Democrat will appear at CMU with an all-star list of figures from academia, business and labor.

They include G. Richard Wagoner Jr., the chairman of General Motors, who brings a real world perspective to the challenges and costs of globalization as his firm looks over its shoulder at Toyota and other rivals for leadership in world auto production.

Lael Brainard, a vice president of the Brookings Institution, worked on global competitiveness issues as deputy director of the National Economic Council during the Clinton administration.

Steve Case, a founder of the former AOL, was one of the architects of the controversial merger of the online firm with Time Inc. Since leaving the company, Mr. Case has turned his attention to philanthropy with the Case Foundation while working to encourage entrepreneurship in the business world.

Eli Broad, another philanthropist and former businessman, has supported bio-medical research and is know particularly for his support of education.

Geoffrey Canada, the CEO of Harlem Children's Zone, is a Heinz Award winner for his work with the social service and education center.

In addition to her work in higher education, Susan Hockfield, the president of the Massachusetts Institute of Technology, is an expert on neuroscience.

Andy Stern, the president of the Service Employee International Union, was an early backer of Mr. Obama's candidacy.

Frederico Pena is a former secretary of transportation and secretary of energy.

Mr. Obama heads to the state backed by a tail wind of strong polling results nationally and in Pennsylvania, potentially a major battleground in November.

A Los Angeles Times/Bloomberg poll released yesterday showed the Democrat leading Mr. McCain by 15 points, 48 percent to 33 percent, in a four-way race including independent candidates Ralph Nader and former Rep. Bob Barr.

In Pennsylvania, where Mr. Obama lost to Mrs. Clinton by 9 points in the Democratic primary, recent polls have consistently shown the Democrat with a general election advantage, although the size of his margin differed significantly in two of the latest surveys.

A Rasmussen survey released this week showed Mr. Obama leading the Republican, 46 percent to 42 percent.

That contrasted with a Quinnipiac Poll released last week that showed Mr. Obama with a surprisingly strong 12-point lead, 52 percent to 40 percent.

The latest national Rasmussen survey showed Mr. Obama leading Mr. McCain, 49 percent to 44 percent, a notably more competitive margin than the LAT/Bloomberg survey suggested.

The Gallup Polls latest daily tracking of the race showed an even closer snapshot, 46 percent to 43 percent.