With his choice of Sarah Palin — the Alaska governor who has advocated drilling in the Arctic National Wildlife Refuge and does not believe in man-made climate change — for vice president, John McCain has completed his makeover from the greenest Republican to run for president to just another representative of big oil.

Compared with his slightly hysterical opponent, Senator Barack Obama, the presumptive Democratic nominee, had been making good sense on energy questions, and his recent speeches had included a menu of proposals for energy efficiency, conservation, alternative fuels and new technologies.

While focusing on alternative energy production, Senator Obama has veered in recent days toward increasing access to fossil fuels, both in seeking to tap the strategic oil reserve and in softening his opposition to offshore oil drilling.

Senator McCain, the presumptive Republican nominee, had earlier dropped his own opposition to offshore drilling, saying that soaring gas prices demanded new approaches. A bipartisan proposal currently before Congress would include more subsidies for alternative energy sources as well as authorization for limited offshore drilling.

Senator Obama, the presumptive Democratic nominee, has until now opposed any expansion of lands for offshore drilling. But at a news conference in Florida, he noted that there had been “very constructive” talks between Senate Republicans and Democrats on the issue in recent days.