As Democratic leaders prepare to bring healthcare legislation before the full House and Senate for votes, they soon must decide who will be taxed to pay for expanding coverage. Legislation emerging from the House would slap a surtax on upper-income people. But many Democrats fear the political fallout over voting to raise anyone's income taxes. The most prominent Senate bill would impose a tax on insurance companies that provide expensive policies, sometimes called "Cadillac" plans. But labor unions oppose the idea, saying the tax would be passed on to workers in the form of higher premiums or shrunken benefits.