When Mitt Romney suggested this week that he pays a lower tax rate than most wealthy Americans do, he refocused attention on his tax proposals — which, like those of his major Republican rivals, would largely cut taxes for the rich while driving down tax collections and widening the nation's deficit.

Romney's tax plan — which calls for permanently extending the Bush administration's tax cuts, reducing the corporate income tax rate and eliminating the estate tax — would cut the taxes of people earning more than $1 million a year by an average of $295,874, according to an analysis by the Tax Policy Center, a nonpartisan research group.

Since Romney would also allow some of President Barack Obama's tax cuts to expire, his plan would effectively raise taxes on some people earning less than $40,000 a year. The Romney tax plan would add to the deficit by reducing federal revenues by $600 billion in 2015, a 16 percent cut, the center found.

Some of Romney's rivals for the Republican presidential nomination are proposing tax cuts that would widen the deficit even more — which was the point that Romney was trying to make Tuesday in South Carolina when he renewed attention to his personal wealth by noting that his effective tax rate is "probably closer to the 15 percent rate than anything."

He explained that most of his income is taxed at the 15 percent rate used for capital gains and dividends, not the rate of up to 35 percent levied on wages and salaries.

Romney had been trying to draw a contrast with Newt Gingrich's plan to eliminate the tax on capital gains, dividends and interest. Romney would eliminate these investment taxes only for married couples with incomes less than $200,000, a provision that he has said would encourage the middle class to save more.

He criticized Gingrich's proposal, saying that it "would not only be a very expensive decision in terms of having to fill an even larger budget hole but would provide for people with very high income the possibility of no tax at all."

Romney is one of the people with high incomes who would benefit from Gingrich's plan. Like others who make large sums of money at hedge funds or private equity firms, Romney earned money from his old firm, Bain Capital, in the form of "carried interest," a share of the profits earned by investors in Bain funds. Under current federal rules, such income is treated as long-term capital gains and taxed at the 15 percent rate — the tax Gingrich would eliminate.

Officials at the Tax Policy Center said they believed that Romney's plan would continue to tax "carried interest" at the current 15 percent rate; the Romney campaign did not respond to a request for clarification.

The tax cuts proposed by Republicans wipe out the budget-balancing effects of the cuts that were agreed to as part of the compromise reached last summer to raise the debt ceiling. Romney's tax plan would add $1.2 trillion to the deficit in just two years.