Wealth is key in candidates' tax platforms

He would also maintain the 15% tax rates on dividends and capital gains for the highest-tier taxpayers. And starting in 2010, McCain would substantially reduce the estate tax. He would increase the exemption on inherited funds from $3.5 million to $5 million and sharply lower taxes on remaining wealth from 45% to 15% -- moves that would enable affluent families to hold on to more of their wealth.

Democratic-leaning economists say McCain's plan offers little new aid to squeezed middle-class families. And they question whether corporations and wealthy Americans would convert McCain-era tax savings into new investments that would bolster the economy.

"McCain does nothing about income inequality," said John Irons, research and policy director for the Economic Policy Institute, a center-left think tank backed by labor interests. "It's skewed toward upper-income Americans to the exclusion of most everyone else."

Obama's tax plan skews the other way, aimed at strengthening benefits for lower-rung taxpayers and raising rates at the top. His plan would restore the Clinton-era rates for the two highest tax brackets to 36% and 39.6%.

In Springfield, Mo., last month, Obama pledged that if "you're a family making less than $250,000 a year, you will not see your taxes go up."

Obama would exempt seniors making less than $50,000 a year from paying any income tax. And he would make the Bush cuts permanent for poor and middle-class Americans, adding tax breaks such as a refundable credit for wage earners and a higher-education credit for students who agree to perform 100 hours of community service.

Under Obama's plan, the highest corporate tax tier would hold at 35% -- a nod to Wall Street but higher than McCain's slashed rate. Obama would raise the highest rate on dividends and capital gains from 15% to 20%. And he would keep the estate tax in the same form approved by Congress for 2009, with an exemption for the first $3.5 million and a top tax rate of 45%. That would mean a higher tax rate on the wealthy than McCain would allow.

As for the onerous alternative minimum tax, both candidates would allow more than 23 million middle-class taxpayers to avoid it by extending a 2007 "patch" that raises the amount of income triggering the AMT. In 2007, the AMT was triggered at $44,350 for single taxpayers and $66,250 for those filing jointly. McCain would increase that income trigger each year by 5%, starting in 2013; Obama would index it for inflation to maintain the patch.