Both presumptive presidential nominees say they are concerned with finding ways to resolve rising energy costs, a slumping economy and concerns about climate change. But the question many are asking is how Barack Obama and John McCain intend to pay for their efforts. At a National Journal forum this morning on the issue of energy policy, key advisers for both candidates offered only vague responses.

McCain's top energy adviser, Douglas Holtz-Eakin, said the Arizona senator would reach political compromises, as he's done in the past, to fund his energy initiatives. Elgie Holstein, Obama's senior energy policy adviser, claimed that the Illinois senator already has support from Congress on most of his energy plans.

The two advisers squared off in Washington's Union Station. Margaret Kriz, National Journal's energy and environment reporter, and Atlantic Media Co. political director Ronald Brownstein pressed the two surrogates on climate change, alternative energy and oil -- a day after President Bush lifted the executive ban on offshore drilling.

Together, these issues constitute "a crisis that will challenge the next president," Kriz told the audience.

Holtz-Eakin sidestepped questions about how McCain would carry out his vision of having 45 additional nuclear power plants by 2030, instead using his remarks to criticize the country's dependence on foreign oil.

When asked about coal, Holstein said Obama would propose funding "technology to develop coal cleanly." (McCain also has voiced his support for so-called "clean coal.") Obama has garnered the support of the environmental community, many of whom have been critical of increasing the country's use of coal.

Yet, for the most part, the surrogates stuck by their candidates' talking points.

Both advisers agreed that the country must move to fund clean energy and that Congress must do its part to fight global warming through cap-and-trade legislation. And both senators agree with the assessment of the scientific community that carbon emissions are contributing to climate change.

The Group of Eight industrialized nations pledged last week to cut greenhouse gas emissions at least 50 percent by 2050, but McCain and Obama say they would do better than that. Obama has said he would reduce emissions about 80 percent by 2050, and McCain's plan seeks about a 60 percent reduction by the same date.

On climate legislation, both Obama and McCain have detailed campaign positions favoring cap-and-trade.

The forum also featured Eileen Claussen, president of the Pew Center on Global Climate Change, and Karen Harbert, managing director of the Institute for 21st Century Energy. The American Coalition for Clean Coal Electricity and the Auto Alliance co-sponsored the forum, and about 100 individuals, mostly from trade associations and media organizations, attended.