House Republicans, fearing a voter backlash, had opposed any approach that smacked of amnesty and chose instead to focus on border security in advance of the elections, passing the fence bill earlier this month.

With time running out, the Senate acquiesced despite its bipartisan passage of a broader bill in May.

Congress also passed a separate $34.8 billion homeland security spending bill that contained an estimated $21.3 billion for border security, including $1.2 billion for the fence and associated barriers and surveillance systems.

“This is something the American people have been wanting us to do for a long time," said Senator Jon Kyl, Republican of Arizona, whose state would be the site of substantial fence construction.

Homeland Security Secretary Michael Chertoff praised the money for border security. He said it would ‘enable the department to make substantial progress toward preventing terrorists and others from exploiting our borders and provides flexibility for smart deployment of physical infrastructure that needs to be built along the southwest border."

Democrats, as expected, ridiculed the fence idea and said a broader approach was the only way to stop further illegal immigration. “You don’t have to be a law enforcement or engineering expert to know that a 700-mile fence on a 2,000-mile border makes no sense,” said Senator Richard J. Durbin of Illinois, the second-ranking Democrat in the Senate. Nevertheless, more than 20 Democrats moved behind the measure.

The fence bill and homeland spending were among security-related measures the Republican leadership was pushing through in the closing hours to bolster their security credentials.

Senator Saxby Chambliss, Republican of Georgia, said the vote would build credibility with conservative voters who have been skeptical of the government’s commitment to border security.

But Republicans and Democrats alike acknowledged they were leaving the country’s immigration problems largely unresolved. The border security measures passed do not address the 11 million people living here illegally, the call for a guest worker program by businesses or the need for a verification program that would ensure that companies do not hire illegal workers.

Instead of trying to reconcile its version of the bill with  the more liberal bill approved by the Senate, the House leadership is pressing with its campaign to reinforce the borders after key lawmakers met recently to assess the critical situation in border states. Based on their report, the House has filed a bill increasing the length of the double fence in the south.

Both proponents of the Senate bill and advocacy groups are agreed that a compromise bill will be approved even after the elections in November. It will be up to the next Congress to revive the bill, if ever.

The attempt to revive the May nationwide rally in favor of illegal aliens has ended in failure as pessimism among advocates has become more pronounced.

The plea of Sen. Edward M. Kennedy, D-Mass., a leading architect of a bipartisan immigration bill in the Senate, for Bush to make an all-out push to rescue the bill before lawmakers quit work to campaign for the Nov. 7 congressional elections went unheeded.

The Senate bill, supported by President Bush, includes a guest-worker program, eventual legalization of the some 12 million illegal aliens already in the US, and toughened enforcement and border security. The House favors cracking down on illegal aliens, stronger border enforcement and other tough measures against violators of US immigration laws.

The House, where its more than 430 members are all up for reelection was in no mood to pass the comprehensive immigration bill.

“I fear that the incentive to demagogue the issue and use it as a political football is going to be greater than the willingness to legislate," said Cecilia Munoz, vice president of the National Council of La Raza, the nation’s largest Latino civil rights organization.

If the current 109th Congress fails to act on immigration by the end of the year, the president would have to start over after the next Congress convenes in early January, when his presidential powers would presumably be on the wane during his final two years in office. Many believe that Bush’s ability to influence legislation has already suffered with his decline in the polls.