Senators announced agreement Thursday on ports security legislation, hoping to approve bolstered protections before November's elections to stop nuclear materials from being smuggled into the country.

The $835 million bill, which has languished in the Senate for years, resembles plans the House approved in May. But it's not clear how Congress will pay for the security measures, including putting monitors at the nation's 22 largest ports to screen for materials to make radiological "dirty" bombs or nuclear weapons.

The agreement among the Senate Finance, Commerce and Homeland Security committees cleared the way for quick consideration by the full Senate. House and Senate aides said they expected the legislation to go to a conference committee to hammer out any differences after Senate approval.

"When we talk to experts, they tell us that our two greatest vulnerabilities that have received inadequate attention are our seaports and our chemical facilities," said Senate Homeland Security Committee Chairwoman Susan Collins, R-Maine. She called the bill a "giant step forward in securing our homeland."

Sen. Patty Murray, D-Wash., said the plan will result in higher security for "every cargo container coming into the country."

Congress made port security an election-year 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 decide to sell the U.S. operations to an American company.

The Bush administration has spent about $10 billion on ports security since the Sept. 11, 2001, attacks. An estimated 6 percent of cargo at the nation's 120 ports is opened for inspection — although about 65 percent is already screened for nuclear or radiological materials, Homeland Security Secretary Michael Chertoff said in an interview last month.

His department aims to increase that number to 80 percent by the end of the year, and to almost 100 percent by the end of 2007. In 2003, few if any cargo containers were screened by radiation monitors, Chertoff said.

"That is, if you compare it to pre-9/11, just a quantum jump forward in security," Chertoff said. "There's just no other way to say it."

The 22 ports to get the monitors under the Senate plan would screen about 98 percent of incoming cargo, Collins said. The bill would also:

— Authorize $400 million in ports security grants.

— Establish a pilot program to screen all cargo headed for the U.S. at three foreign ports.

— Create a "green lane" to expedite incoming cargo from previously approved manufacturers and other business partners.

The House bill, which called for spending $5.5 billion over five years, would pay for the security with existing Customs fees. But the Senate Finance Committee has rejected doing so.