House Ways and Means Committee Chairman Charlie Rangel, D-N.Y., said Friday that the plan -- which Democrats expect to present in detail Monday -- could generate as much as $540 billion over 10 years. Married taxpayers earning more than $350,000 a year in adjusted gross income and single filers making more than $280,000 a year would pay a surtax of about 1 percent. The added tax would be higher for people in higher income brackets. The tax plan still faces an uncertain fate in the House and in the Senate, where Democrats and Republicans are working on their own proposals to offset the costs of helping tens of millions of people get health insurance. Senate leaders have shown much less interest in a new income tax. President Barack Obama, meanwhile, has proposed raising more than $300 billion over 10 years by limiting the deductions that wealthy Americans take on their income taxes. Funding has emerged in recent weeks as one of the most politically explosive parts of the emerging health care debate on Capitol Hill. And it has slowed the advance of health care bills in both chambers as senior Democrats look for ways to hold together their own party and keep powerful interest groups from turning against their campaign to overhaul the health care system. On Friday, senior House Democrats sought to reassure moderate 'Blue Dogs' and other centrist lawmakers who have charged that the health care bill being pushed by party leaders does not do enough to bring down costs, protect small businesses and boost payments to rural health care providers. 'Their concerns will be reflected in changes were are making,' said House Energy and Commerce Committee Chairman Henry Waxman, D-Calif., one of three lead authors of the House health care bill who met with moderates Friday. 'I think we made some good progress.' Waxman said revisions to the bill would exempt more small businesses from having to pay any fees if they do not provide insurance to their employees and include more changes in Medicare to bring down costs. 'They made a good case ,' he said, expressing optimism that the House would be able to finish its work on the bill before lawmakers leave for their August recess. Speaking from the G8 summit in Italy on Friday, Obama insisted that health care legislation is still on track despite a week of fits and starts on Capitol Hill. 'There are going to be some tough negotiations in the days and weeks to come, but I'm confident that we're going to get it done,' Obama told reporters at a news conference in Italy. 'We're closer to that significant reform than at any time in recent history.' The president, who called health care his 'highest legislative priority' over the next month, said he would be working to allay fears about the impact of a health care overhaul. 'We have a long history in America of scaring people that they're going to lose their doctor, they're going to lose their health care plans, they're going to be stuck with some bureaucratic government system that's not responsive to their needs,' Obama said. 'And overcoming that fear, fear that is often actively promoted by special interests who profit from the existing system, is a challenge.' 