President Bush has vetoed a bill that would expand a popular government-run health insurance program for children.
The veto is only the fourth during the president's nearly seven years in office and sets up a showdown with Congress, which overwhelmingly supported the bill.
Mr. Bush has said the measure is "irresponsible" and "would dramatically expand the program beyond its original intent."
The Democratic Party-controlled Congress approved expanding the program by $35 billion over five years. Under the measure, the State Children's Health Insurance Program (S-CHIP) would provide health coverage for about 10 million children in low-income families not able to afford private insurance but earning too much to qualify for federal programs.
The bill calls for the federal tax on cigarettes to be raised 61 cents, to $1 a pack, to help pay for the expansion. The measure is supported by both Democrats and members of Mr. Bush's Republican party, but it is not clear if it enjoys enough support to override the president's veto.
At least four million children are currently covered by the S-CHIP program. The United States is one of the few wealthy countries with no universal health care program.
Some information for this report was provided by AP.