Washington ? Republicans reacted angrily Thursday to President Bush’s promise to veto a bill that would renew and expand the popular State Children’s Health Insurance Program, raising the likelihood of significant GOP defections when the package comes to a vote next week.

“I’m disappointed by the president’s comments,” said Sen. Charles Grassley, R-Iowa, who urged Bush, in an early morning telephone conversation Thursday, to support the emerging bipartisan compromise. “Drawing lines in the sand at this stage isn’t constructive. … I wish he would engage Congress in a bill that he could sign instead of threatening a veto.”

“I’m very, very disappointed,” said Sen. Gordon Smith, R-Ore. “I’m going to be voting for it.”

With the program about to expire Sept. 30, Bush said in a news conference that he would reject the $35 billion funding expansion being cobbled together by House and Senate negotiators. He said the bill would inappropriately extend coverage to children in families with incomes of up to $83,000 a year, prompting many to drop private insurance. He urged Congress to pass instead a temporary extension of the program until a more lasting compromise can be worked out.

“Members of Congress are putting health coverage for poor children at risk so they can score political points in Washington,” Bush said, adding later that “health coverage for these children should not be held hostage while political ads are being made and new polls are being taken.”

But members of both parties countered that it is the president who is jeopardizing children’s health. They said most Americans, including many GOP governors and groups such as the AARP, support expanding the program’s enrollment to about 10 million, up from the 6.6 million it serves now.

Some GOP lawmakers could face considerable pressure to defy the president when the measure comes to a vote. Lawmakers are confident of veto-proof passage in the Senate, but getting the required 290 votes in the House appears to be a long shot.

Rep. Ray LaHood, R-Ill., said he is trying to get 20 to 30 House Republicans to vote for the compromise – enough, he hopes, to persuade Bush to reconsider.

“I’m optimistic we can get a significant number of Republicans,” LaHood said. “It’ll be a good vote for them. They can go back home and trying to assuage the feelings of their constituents who have heartburn about their views on the war or other things. And it shows that if they feel strongly about something, they are willing to stand up to the president and tell him.”