DEFICIT SPENDING didn’t bother the Bush administration when the issue was tax cuts. Congress had no trouble finding “savings” to supposedly offset new costs when the costs were in a corporate tax bill stuffed with special-interest provisions. But when it comes to health care for poor children, different, stricter rules seem to apply. This week’s lame-duck Congress is poised to leave town without taking any action to restore $1 billion in federal funding for children’s health care that wasn’t used before its Sept. 30 expiration and therefore reverted to the Treasury. Republican lawmakers say they don’t oppose renewing the funding but insist that it has to be paid for with cuts elsewhere. The result is that some 200,000 low-income children will be at risk of losing health coverage in the next three years.The issue involves the State Children’s Health Insurance Program (SCHIP), which was launched in 1997 to help states provide coverage to low-income children whose families earn too much to be eligible for Medicaid. With $40 billion in federal matching funds over 10 years, this was the largest expansion of health coverage for children since the adoption of Medicaid in the 1960s; last year alone the program enrolled 5.8 million children. Even as the share of Americans without health insurance is growing, the percentage of children lacking coverage has stayed stable, in large part thanks to Medicaid and SCHIP.