WASHINGTON - Congress approved legislation Thursday that would potentially add 4 million children to a popular health care program, setting up a veto fight that President Bush probably will win but handing Democrats a campaign issue for next year's elections. Eighteen Republicans in the Senate lined up with Democrats in voting 67-29 to increase spending on the State Children's Health Insurance Program, or SCHIP, from about $5 billion to $12 billion annually for the next five years. The vote was enough to override a promised Bush veto. But supporters in the House, which passed the bill Tuesday, are about two...