House leaders insisted Tuesday that they still hoped to negotiate with the Senate. But the schedule for the hearings, set for July and August across the country, makes it unlikely that the two chambers can reach a final agreement before the November elections.

When Congress reconvenes in September, most lawmakers will be preoccupied with their campaigns; traditionally, little important business gets done at that time.

Failure to produce a bill would be a huge setback for Bush, who has prodded lawmakers to pass immigration legislation that — like the Senate legislation — would toughen border enforcement but also create a guest worker program and offer millions of illegal immigrants a way to gain legal status.

Democrats interpreted the House decision to hold town-hall-style meetings as an effort to stop the Senate legislation.

"The Republican House wants to defeat the immigration bill," Senate Minority Leader Harry Reid (D-Nev.) said. "This is a stall."

House Republicans denied the charge, arguing that they needed the time to review the legislation.

House Speaker J. Dennis Hastert (R-Ill.) "believes that we should focus on getting a bill done right and not be pressured by some during an election year," said his spokesman, Ron Bonjean.

He added that the House would select negotiators to work on a final bill only "after we go through the Senate … bill with a fine-tooth comb."

House leaders informed Bush of their plan a few days ago, aides said, although Senate Majority Leader Bill Frist (R-Tenn.) had known about it for several weeks.

A spokeswoman for Frist, Carolyn Weyforth, said her boss welcomed the hearings and the desire of House members to have time to catch up on the Senate bill.

When asked whether he thought the call for hearings was an attempt to kill the Senate version, Frist said, "I don't think so."

But in announcing the hearings, House Majority Leader John A. Boehner (R-Ohio) said one purpose would be to discuss "provisions in that bill that I have concerns about."

The move comes as Republicans are seeking to energize their core voters in the months before the midterm elections.

This month, Brian Bilbray, a Republican from Carlsbad in San Diego County, won the House seat vacated by disgraced Rep. Randy "Duke" Cunningham by campaigning almost entirely on the need to get tough on illegal immigration.

His victory encouraged House conservatives, who say border security and enforcement must come first.

Rep. Tom Tancredo (R-Colo.), the leader of a 101-member caucus that advocates tough enforcement, interpreted the scheduling of the summer hearings as a sign that House leaders had little desire to try to find common ground with the Senate.

"Odds were long that any so-called compromise bill would get to the president's desk this year," said Tancredo, citing the tight legislative schedule and the distance between the House and Senate approaches to immigration. "The nail was already put in the coffin of the Senate's amnesty plan. These hearings probably lowered it into the grave."

Tancredo added that the hearings were designed to build support for an enforcement-only approach adopted by the House in a bill it passed in December.

"This is an issue that we can run on and win in November," Tancredo said. "By training Americans' focus on the Senate's amnesty pact, we'll create momentum for an enforcement-first bill after November. As more light is shed on the Senate's bill, more and more Americans find reasons to oppose it."

Boehner and his staff said that the hearing dates and locations had not been decided, but that they would involve several House committees that hold jurisdiction over different aspects of the bill.

Some of the hearings are expected to be held in areas in the South and Southwest where the immigration issue has been particularly divisive.

A Boehner spokesman detailed a few of the Senate provisions that might be examined in the hearings. They include a measure that would allow immigrants who gain legal status to receive Social Security benefits for work they did while illegal, and another that would require immigrants eligible for legalization to pay back taxes.

Even before the hearings were announced, progress on a final bill was stymied by a procedural problem that is blocking the Senate from choosing negotiators to work with the House.

Republicans and Democrats blame each other for the delay, which shows no sign of resolution.

Senate Republican aides said Tuesday that they doubted there would be much movement on the issue until the House hearings were completed. And some senators said they thought it was a good idea for the House to take the time to consider the Senate version.

"The problem with the Senate bill is that it is a tremendously important issue that had very little serious thought given to it," said Sen. Jeff Sessions (R-Ala.), who voted against the measure. "The House can provide the nation an opportunity to find out what's in the bill."

One architect of the Senate bill said that since the House had only debated enforcement measures, the hearings might offer members a chance to learn about a broader overhaul.

"I realize that the House has not addressed two of the three major aspects of the Senate bill," said Sen. Mel Martinez (R-Fla.), who added that he was optimistic about the Senate's approach.

Sen. Dianne Feinstein (D-Calif.) said some delay might help the chances of getting a bill with a guest worker program and path to legalization through Congress.

"My own view is that Republicans want to use it as a campaign issue," she said. "I think it is a good idea to let this thing settle for a while."

Sen. John Cornyn (R-Texas), a critic of the Senate bill, said some Republicans wanted to put off the discussion until after election day, when Congress will likely hold a lame-duck session. He added that backers of the Senate bill would have to accept some compromise.

"I think it's clear the Senate will have to move closer to the House position to get it resolved," Cornyn said.

But many saw the hearings as an attempt to scuttle the immigration overhaul altogether.

"This is clearly a delay tactic by the House Republicans, who have been dead set against comprehensive reform from the beginning," said Sen. Edward M. Kennedy (D-Mass.), an author of the Senate legislation. "One has to wonder why there are going to be continued hearings … other than just to delay and kill the bill."