By E. J. Dionne Jr.

This week's showdown over children's health insurance is the first skirmish in the new battle for universal health coverage. It is also the first confrontation between the president and Congress fought out almost entirely on terms set by the new Democratic majority.

On no spending issue do Democrats have broader public support -- or more Republican allies -- than on expanding the State Children's Health Insurance Program. That is why they have chosen this as the issue on which they want to take their first stand.

Bush, in the meantime, has confirmed what was clear when he was governor of Texas but little noted when he first ran for president: When it comes to expanding government-sponsored health insurance for low-income kids, he is a skeptic. Health and Human Services Secretary Mike Leavitt coined a new word last week by saying that it's "the ideologic question that we want to focus on." He was candidly describing an administration dug into a posture that even conservative Republicans in Congress reject.

On its face, Bush's fight over SCHIP seems oddly chosen. The program provides coverage for children from families too poor to afford private insurance but not eligible for Medicaid. In many ways, it is a Republican creation. It made it through a GOP Congress in 1997 thanks to the work of Sen. Orrin Hatch (R-Utah), who is now furious about Bush's veto threat.

By virtually all measures, the program has achieved exactly what it promised, and at a reasonable cost. But Bush argues that the $35 billion, five-year expansion of the program, worked out between the Democrats and such leading Republicans as Hatch and Sen. Chuck Grassley of Iowa, might push too many children into government insurance. Bush wants a $5 billion expansion over five years, which the Congressional Budget Office says would eventually shove more than 1 million children out of the program at a moment when the number of children without health insurance is growing after years of decline. (That decline, by the way, was due in significant part to the success of SCHIP.) The goal of Hatch, Grassley and the Democrats is to expand the program to 10 million children from the roughly 6.6 million covered now.

This battle is central to the long-term goal of universal coverage. If a proposal with broad bipartisan support that is friendly to state governments and covers the most beloved group in society -- children -- can't avoid being gutted for ideological reasons, what hope is there for a larger health compromise?

Bush has been here before. He now says he wants to make sure the program is limited to children from families at 200 percent of the poverty level (roughly $41,300 a year for a family of four). But as governor of Texas, he wouldn't even go that far, seeking to limit coverage under SCHIP to families at 150 percent of the poverty line. Democrats in the Legislature finally pushed him to 200 percent. Bush was putting up his resistance in 1999, when Texas ranked second to last among states in the percentage of uninsured children.

Democrats feel confident in picking this fight because any presidential claim that this is a battle about fiscal responsibility (the difference between the president and Congress is roughly $6 billion a year) is belied by the president's $200 billion request for Iraq and Afghanistan for this year alone. Democrats are arguing that 41 days' worth of Iraq spending would provide health coverage for 10 million children each year -- not a comparison the administration relishes.

In theory, SCHIP expires at the end of the month. Senate Republican leaders clearly fear that the president's expected veto would be seen as throwing children off the health insurance rolls. Therefore, they have insisted, in advance of a vote on the bill, that Democrats agree to grant a temporary extension if Congress fails to override Bush. This reduces the Democrats' leverage but is also a concession that Republicans know how vulnerable the administration is.

There are other pressure points. If Bush won't do business with the Democrats on a children's health bill, he could poison efforts to renew his No Child Left Behind education program, which also expires at the end of the month. Bush needs Democratic votes for renewal because of Republican defections. Rep. Rahm Emanuel (D-Ill.), one of the leading sponsors of the children's health bill, could not resist arguing that "it's a bizarre thing that a president who believes in testing kids for math does not believe in testing kids for measles and mumps."

Democrats are placing a lot of chips on SCHIP. Only moderate Republicans and compassionate conservatives willing to challenge Bush's veto can save their party from the president's anti-SCHIP obsession.