CHICAGO (AP) -- Democratic Sen. Barack Obama said Thursday that Sen. John McCain reversed his position on President Bush's deep tax cuts in order to win the Republican presidential nomination, one of his sharpest criticisms yet of the Arizona senator he hopes to face this fall.
Criticizing GOP efforts to extend major tax cuts from Bush's first term and to eliminate the estate tax, Obama said: "These are all steps that John McCain rightly said were irresponsible when they first came up."
"He made a decision to reverse himself on that," Obama told reporters as he flew from Chicago to Washington for a series of Senate votes on budget issues.
"That was how, I guess, you got your ticket punched to be the Republican nominee," he said of McCain. "But he was right then, and he's wrong now."
McCain has said he supports extending the tax cuts, which he initially voted against, because the economy is struggling and tax reductions offer some stimulus.
McCain spokesman Brian Rogers said in a statement that if Obama is nominated, "the American people will have a clear choice: John McCain will cut taxes while Senator Obama will raise them, hurting our economy and costing jobs for hardworking Americans."
Obama has proposed an array of subsidies for higher education, health care and other costs hitting middle-class families. He said he believes he can pay for such plans by closing tax loopholes, placing a new tax on carbon emissions, phasing out the Iraq war and ending the Bush tax cuts for the nation's highest earners.
"We have identified the cuts that we think are available, or the changes in our tax code that are available to pay for our middle-class tax cut as well as our proposals to fund higher education and so on," the Illinois senator said.
He said, however, "There will be a lot of special interests and lobbyists that will resist the kinds of changes that I've proposed."
Asked if he would scale back his agenda if some of his proposed tax increases fail, Obama said, "I am a strong believer in pay-go," a term for avoiding new deficits by paying as you go. "So adhering to pay-go means that if I couldn't find the revenues or reduce spending in other areas, then I couldn't pay for my proposals."