House Democratic leaders on Monday afternoon sought to deflect criticism of their forthcoming health care overhaul, arguing it would lower costs and enhance coverage for the middle class. And the Democrats — who plan to officially unveil their bill as early as Tuesday — defended a proposed tax increase on the rich to pay for it.“Middle-income people are not touched— by the tax increase, Speaker Nancy Pelosi (D-Calif.) said.The Democratic bill would provide a host of benefits for middle-class people, including eliminating pre-existing conditions and the fear that they would lose their insurance if they lose their jobs, Pelosi said. “This is about the middle class in our country,— she said. “Lower their costs, improve their quality, expand their coverage and do so in a way that gives them piece of mind. … This is about them.—Democratic leaders said their bill would be marked up this week in House committees and passed out of the chamber later this month; they argued it would improve quality, reward prevention and dramatically expand insurance coverage.The bill would eliminate the “doughnut hole— in the Medicare prescription drug benefits and provide large tax breaks to small businesses that buy coverage, Democratic leaders said.Republicans, meanwhile, have slammed the proposed tax increase as damaging to the economy and have attacked the overall package as a government takeover of health care.House Ways and Means Chairman Charlie Rangel (D-N.Y.) said last week that the tax increase would raise $540 billion over a decade and would affect families making more than $350,000 a year starting in 2011.