Barack Obama says John McCain's plan to balance the budget doesn't add up. Easy for him to say: It's not a goal he's even trying to reach.

Not only does Obama say he won't eliminate the deficit in his first term, as McCain aims to do, he frankly says he's not sure he'd bring it down at all in four years, considering his own spending plans.

"I do not make a promise that we can reduce it by 2013 because I think it is important for us to make some critical investments right now in America's families," Obama told reporters this week when asked if he'd match McCain's pledge.

So what is more important in tough economic times? For the government to spend more to help hard-hit Americans or to eliminate a deficit that can lead to higher borrowing costs and slow the economy?

Whether it's McCain the Republican or Obama the Democrat in the White House next year, the new president is likely to inherit an annual federal deficit exceeding $400 billion. Budget watchers say it's hard to figure what either candidate's impact will be since neither is offering full details of his spending programs.

"I think both candidates need to put some numbers on these things so we can get a sense of how realistic they are," said Robert Bixby of the Concord Coalition, a budget watchdog group.

Obama's criticism of McCain's pledge as "overly ambitious" is backed up by fiscal experts.

"Hypothetically it's possible to get to a balanced budget by 2013, but not under the policies that McCain has proposed," Bixby said. "The policies he would propose would actually add to the deficit when you take them all together."

Jim Horney, director of federal fiscal policy at the Center on Budget and Policy Priorities, said the center's analysis, even assuming a fast drawdown of troops in Iraq, found McCain would have to cut around $400 billion worth of federal programs to balance the budget by 2013.

"It seems unlikely, particularly given that Senator McCain has not been willing to be specific about what programs he would cut," Horney said. "And even if he were willing to, there's a real question of whether the Congress or the public would go along with the kinds of cuts required to balance the budget, assuming the tax policies that he's proposing."

McCain says he would reduce spending by slowing the growth of Social Security, Medicare and Medicaid, but he hasn't said how he would try to change the benefits. He also says he would slow the government's spending growth and stop spending on lawmakers' special earmarked projects. But earmarks accounted for just $17 billion of the $2.9 trillion budget this year. Continued...