Radiating cautious confidence, officials with the presidential campaign of Sen. Barack Obama (D-Ill.) said Friday they continue to be on offense in GOP strongholds, forcing Republican presidential candidate Sen. John McCain (Ariz.) to expend resources defending territory and scale back efforts in states that had been battlegrounds.

Speaking to reporters, Obama campaign manager David Plouffe said McCain, who earlier this month withdrew from Michigan, had reduced his effort in Wisconsin, Minnesota and New Hampshire, though McCain did campaign in New Hampshire this week.

Plouffe said the Obama campaign was focusing heavily on Pennsylvania, where Obama aides believe McCain is making an aggressive stand. And the Obama campaign is pressing its efforts in Iowa, New Mexico, Virginia and Colorado, states President Bush won in 2004 but where Obama leads in polls.

Plouffe also expressed optimism about Florida and Ohio, major states taken by Bush and where Obama’s lead might be more tenuous. He said the focus on the economy in the campaign would help Obama in Ohio, and that early voting in Florida was helping erase the GOP’s traditional advantage in absentee voting in the state. Plouffe said he was “thrilled” with Obama’s position in North Carolina and Indiana, traditionally GOP-leaning states now rated as tossups.

Jon Carson, the campaign’s national field director, said Democrats were dominating the early voting in key states such as Iowa and New Mexico. But a Gallup tracking poll Friday said early voting nationwide is about equal among McCain and Obama supporters.

Meanwhile, President Bush and first lady Laura Bush voted Friday without fanfare, mailing their ballots to Texas authorities. In an e-mail titled “I find this hard to believe,” White House press secretary Dana Perino said she was forced by numerous inquiries to confirm that Bush and his wife voted for McCain.