Congressional Republicans pushed Friday for passage of a major ports security bill, giving lawmakers something to add to their resume as they head home for an election expected to be dominated by security issues.

Democrats, while generally behind the ports security bill, complained that it failed to address rail and mass transit, another area considered highly vulnerable to terrorist attack. They also complained that Republicans were using the bill as a vehicle for other GOP-backed measures.

House and Senate negotiators said late Thursday they had reached tentative agreement on the ports aspect of the legislation, which outlines steps to protect the nation's 361 ports from what could be catastrophic attacks from chemical, biological or nuclear devices.

If a final compromise is reached, the two chambers could vote on it Friday or Saturday, before Congress begins a five-week recess for the Nov. 7 elections.

With an eye to the election, Congress has concentrated on security-related issues in the past two weeks, considered measures on military tribunals, President Bush's wiretapping program, spending for defense and homeland security and a bill to build a 700-mile fence along the Mexican border.

The ports bill was still being drafted early Friday, but aides said it may include a court security bill championed by House Speaker Dennis Hastert, R-Ill., and legislation to limit Internet gambling.

There also was a proposal to give legal immunity to telecommunications companies that give subscriber records to the government.

"We had a chance to get more screeners at our nation's airports, add more security for our transit systems and protect cargo and people as they traverse the country by rail," said Sen. Frank Lautenberg, D-N.J. Instead, Republicans "are trying to stuff the legislation with gifts to special interests and large corporations."

"Republicans have once again shortchanged America by leaving our rail, mass transit and aviation systems vulnerable," said Rep. Bennie Thompson of Mississippi, top Democrat on the Homeland Security Committee.

Democrats were upset that the final version apparently would drop provisions in the original Senate bill that approved $4.5 billion for rail and mass transit security. They pointed to terrorist attacks on rail systems in London, Madrid, Spain, and Mumbai, India, formerly known as Bombay, as evidence of the vulnerability of American railways.

But Sen. Susan Collins, R-Maine, chairwoman of the Senate Homeland Security and Governmental Affairs Committee, said the port bill "will make a real difference to the security of our country," adding new layers of protection for the 11 million cargo containers that enter the nation every year.

Collins said the bill would include approval of $400 million a year over five years for risk-based grants for training and exercises at ports.

It would require the nation's 22 largest ports, which handle 98 percent of all cargo entering the country, to install radiation detectors by the end of next year.

Pilot programs would be established at three foreign ports to test technology for nonintrusive cargo inspections. Currently only one foreign port, Hong Kong, scans all U.S.-bound cargo for nuclear materials.

The Homeland Security Department would be required to set up protocols for resuming operations after an attack or incident. It is feared that a terrorist attack, such as a nuclear device set off by remote control, could cripple the entire economy as well as cause massive casualties.

The bill would authorize $3.4 billion over five years for ports security.

Democrats said that was still short of what was needed. "We inspect just 5 percent of incoming shipping containers, while 95 percent gets into our country without us knowing what's inside," Lautenberg said.

Congress made port security a priority after a February fight over a buyout that put a Dubai company in control of some operations at six American ports. The outcry led the Dubai company, DP World, to sell the U.S. operations to an American company.