s version emphasizes border security. House leaders object to a provision in the Senate bill that would give many illegal immigrants citizenship.

"Our No. 1 priority is to secure the border, and right now I haven't heard a lot of pressure to have a path to citizenship," House Speaker Dennis Hastert, R-Ill., told the Associated Press.

Hastert's decision, which jeopardizes final action on a bill this year, came as Bush was traveling to Europe for a summit meeting with leaders there. White House deputy press secretary Dana Perino said the president remains "undeterred in his effort to pass an immigration reform bill." Other Republicans are less optimistic about chances that legislation will pass before Congress adjourns for the fall elections.

"It's going to be difficult," said Sen. Sam Brownback, R-Kan. House Majority Leader John Boehner, R-Ohio, agreed. Asked whether he thought immigration legislation would become law this year, he said, "Maybe."

Normally, the next step in the legislative process is for a House-Senate conference committee to hammer out differences between the bills. That won't happen until September at the earliest, according to Hastert spokesman Ron Bonjean. "Before the speaker will appoint conferees, he wants to get to the bottom of the Senate Kennedy bill," Bonjean said.

Bonjean's characterization of the Senate bill, identifying it with Sen. Edward Kennedy of Massachusetts, an icon of Democratic liberalism, reflects the deep divisions in the Republican Party over immigration. In fact, the Senate bill was co-sponsored by a number of prominent Republicans, including Sens. John McCain of Arizona, Chuck Hagel of Nebraska and Brownback.

Brownback expressed dismay at the news that Hastert will not begin negotiations with the Senate until the fall. "I am OK with hearings, but don't stall the process," he said. "This is a bill that is going to need a lot of conference time."

Bush has been urging Congress to move quickly on immigration. "I don't think this issue can wait," he said in Nebraska this month. "It needs to be addressed now."

He has endorsed the basic outline of the Senate bill, including plans to allow immigrants who have lived in the country illegally since at least 2004 to become citizens. "To me that is a humane, decent way of addressing a very difficult problem," he said at his Nebraska appearance.

Many House Republicans feel differently. House Judiciary Committee Chairman F. James Sensenbrenner, R-Wis., has said giving illegal immigrants citizenship amounts to amnesty for lawbreakers.

Further complicating the outlook for the immigration bill: a special election for a Southern California congressional seat that Republican Brian Bilbray won with a campaign that emphasized his opposition to illegal immigration. Angelo Amador, director of immigration policy for the U.S. Chamber of Commerce, which supports the Senate bill, says the Bilbray election may have given Republicans cold feet about striking a deal on immigration: "They're going back and forth trying to decide what's best for them."

Kennedy called Hastert's decision a "cynical delay tactic."

Contributing: Richard Benedetto