President Bush intends to use the State of the Union address on Tuesday to battle the rising cost of health care with a one-two punch: tax breaks to help low-income people buy health insurance and tax increases for workers whose health plans cost more than the national average. The basic concept of the president's plan is that employer-provided health insurance would no longer be entirely tax-free. Workers could be taxed if their coverage exceeded limits set by the government. The plan is a startling move for a president who has repeatedly pledged not to raise taxes. And it is certain to run into opposition from business groups, labor unions and, most of all, the Democrats who now run Capitol Hill.