Senate Republicans on Wednesday rejected a Democratic attempt to attach dozens of national security programs to legislation intended to protect seaports.

The Democrats' proposal had threatened the overall ports security bill, which would install monitors at the 22 largest ports. These devices would screen for materials used to make radiological bombs or nuclear weapons.

The ports bill could come to a final vote on Thursday.

The plan by Democratic leader Harry Reid would have put Republicans in the awkward position of opposing security measures that many people in the United States believe are long overdue. Examples include improving safeguards on trains and buses and at chemical plants.

"Politics won't protect the American people," Reid, D-Nev., said after the GOP-controlled Senate defeated his plan.

Democratic Sens. Bill Nelson of Florida, Ben Nelson of Nebraska and Mark Pryor of Arkansas voted against Reid's proposal.

"It is an interesting hodgepodge of provisions that are irrelevant to the underlying bill," said Sen. Susan Collins, R-Maine. "What it does not include are provisions that have to do with port security."