Democrats and Republicans are entering a political debate over a $700 million health plan offered by Jay Nixon, a Democrat running for governor of Missouri. Nixon wants to reinstate Medicaid for about 100,000 low-income adults, restore services such as dental care, and expand children's coverage. He says the state can absorb its share of the cost, while the federal government would pay the rest. Republican budget leaders are calling Nixon's plan an expansion of welfare, and estimate it would cost the state as much as $400 million a year.