WASHINGTON (AP) -- Republican efforts to scale back expansion of a popular children's health insurance program failed in the Senate Wednesday, as a bitter partisan battle unfolded in the House over a more generous version that includes broad Medicare changes.

The Senate rejected, 53-42, an amendment by Sen. Judd Gregg, R-New Hampshire, that would have cut federal payments for middle-income children and childless adults under the State Children's Health Insurance Program -- originally designed to cover only poor kids -- and limit future coverage for those populations.

Earlier, the Senate defeated, 58-26, an amendment by Sen. John Ensign, R-Nevada, that would have shifted the bill's $35 billion SCHIP increase, financed through a tobacco tax increase, into treating diseases like cancer and heart disease. It would have left the program, slated to expire on September 30, funded at its current $25 billion level for the next five years.

The action came as House Republicans slowed the chamber to a crawl through parliamentary tactics in protest of a $75 billion SCHIP bill they derided as the first step in moving toward government-run universal health care.

Both versions are under veto threats from President Bush, who calls them overly expensive and an inappropriate shift away from private health insurance.

"The real plan here is to set the stage for a movement of the next gigantic step in the direction of what should be called Hillary-care -- national socialized medicine," said Rep. Jerry Lewis, R-California, referring to the failed Clinton administration health care effort, directed by then-first lady Hillary Rodham Clinton.

Democrats are using the legislation as an opportunity to roll back years of Republican-driven changes to Medicare, cutting payments to Medicare HMO's and shifting the money to doctors and benefits for low-income seniors. They painted the GOP opposition as mean-spirited attempts by their political foes to deprive children of health insurance.

"Health care for America's children cannot be delayed or denied," said Rep. Kathy Castor, D-Florida, as Republicans worked to stall the legislation through time-consuming procedural votes.

In the Senate, the picture is far different. There, home-state politics are colliding with Bush's health care agenda, prompting Republicans to line up with Democrats on expanding the children's health insurance program.

In threatening to veto the Senate measure, Bush argued it spends too much and covers too many middle-income people.

He faces an uphill battle in persuading Senate Republicans, whose states have come to rely on the program to cover an ever-larger chunk of their constituents, to accept a less expensive version.

The $60 billion measure is on track to pass the Senate this week with wide bipartisan support. Bush had proposed spending half that on the program.

Sen. Trent Lott, R-Mississippi, the party whip, said his hunt for the votes to sustain a Bush veto is a challenge given senators' parochial interest in the program. It takes two-thirds of senators present and voting to override a veto, leaving Republicans in search of up to 34 votes to deny Democrats that chance.

"I thought this was the United States Senate, and if it is the United States Senate -- which I have my doubts about -- you vote against a program, even if it means more money for your state, if it's bad," Lott lamented. "But I don't think we do that anymore."

Lott and Minority Leader Mitch McConnell, R-Kentucky, offered a scaled-down, $35 billion alternative that would limit eligibility for the program to those it was originally designed to cover -- people at 200 percent of poverty, or $41,300 for a family of four.

Since the program's inception, the Bush administration has issued waivers to several states that allowed them to extend coverage to children with higher incomes and to adults. Nineteen states have done so, allowing families earning as much as $82,600 to be covered.

Republicans accuse Democrats of using the program as a way to extend government health insurance to millions of people. In a veto threat issued Monday, the administration said the measure "essentially extends a welfare benefit to middle-class households" and "goes too far in federalizing health care."

The bipartisan bill would gradually move adults who don't have children out of SCHIP, giving states the option of covering them through Medicaid. The government also would lower payments for parents' coverage and be barred from issuing new waivers allowing states to cover parents. But states would still have the option of providing coverage to pregnant women through SCHIP.

In the Senate, many Republicans say they're sympathetic to Bush's criticism that the measure covers adults and children it was never intended to, but those worries take a back seat to their states' interests.

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Copyright 2007 The Associated Press. All rights reserved.