A port security bill that’s five years in the making is facing two formidable foes this week: politics and perfection.

U.S. Sen. Patty Murray, D-Wash., has teamed with U.S. Sen. Susan Collins, R-Maine, to produce a measure that gives seaports the kind of security scrutiny that has been reserved for air travel since the Sept. 11, 2001, terrorist attacks.

The GreenLane Maritime Cargo Security Act would set aside $835 million annually for five years to employ the latest cargo inspection technology, hire more security personnel and install the improved gates, fences and other infrastructure that port officials have been clamoring for since 2001. Airports have gotten $20 billion since the terrorist attacks. The bill would be paid for by tapping customs fees that ordinarily go to the general fund.

The bill’s GreenLane provision is a voluntary program that importing companies can join to make sure their just-in-time resupply strategy isn’t upset by inspections. In exchange for certifying their cargo is sealed and safe at the point of departure from a foreign seaport, companies are assured their products won’t be stalled at U.S. docks by inspections.

Homeland Security Chief Michael Chertoff has testified in support of the bill. So has the shipping industry. The U.S. House has passed a similar measure, but this is election season and thus politically charged amendments could torpedo the bill.

One such amendment was launched by U.S. Sen. Charles Schumer, D-N.Y., this week. It calls for 100 percent of containers to be inspected within four years. Companies would be charged $8 per container to pay for it.

Murray correctly notes that with today’s technology such a standard would result in huge logjams at ports and an immediate hit to the U.S. economy. Plus, companies could always avoid Seattle and other U.S. ports and send cargo to Canada or Mexico, where it would then be placed on trains and trucks without all of it being inspected.

U.S. Senate Minority Leader Harry Reid, D-Nev., wants to expand the bill to include beefed up security for railroads, chemical plants and other sites. That’s worth considering in a bill of its own, but tacking on those provisions at this late date will only tie the bill into knots.

Killing this bill might be the goal of these amendments, because the Republicans have made it a priority to pass homeland security legislation that they can tout on the campaign trail. But, as Sen. Murray points out, port security is more important than electioneering.

Under the bill, the 22 busiest ports would be outfitted with the latest in radioactivity-detecting scanners. About 98 percent of cargo would be scanned for radioactivity. That’s vital, because a Homeland Security Department study found that the initial blast from a nuclear bomb hidden in a container would kill an estimated 60,000 people in the Long Beach area. The spread of radiation would claim more victims, cause the evacuation of the entire Los Angeles basin and devastate the region for years.

Make that Seattle or Tacoma, and Washington state would become an economic wasteland.

This bill provides overdue protections for the nation’s ports. It sets realistic goals and guidelines based on today’s technology. The Senate should pass it.