WASHINGTON – Congressional Republicans aimed for a post-midnight vote Friday on a major ports security bill, capping a rush to complete security-related legislation before lawmakers leave to face the voters in the midterm elections.

The ports bill, aimed at making the nation’s 361 seaports safer from biological, chemical or nuclear attacks, was to be the last vote taken by the House before its five-week break for the elections. The Senate could approve the bill today.

“In the post-9-11 world we have to strengthen security at our ports,” said Rep. Peter King, R-N.Y., chairman of the House Homeland Security Committee.

Democrats, while generally in favor of the bill, complained that it failed to address rail and mass transit, other areas considered highly vulnerable to terrorist attack. They also said Republicans were using the bill as a vehicle for other GOP-backed measures.

Debate on the bill was delayed as negotiators wrangled over other legislation that might be added.

“They’re using it as a dumping ground” for bills that couldn’t pass on their own, said Jim Manley, spokesman for Senate Democratic leader Harry Reid of Nevada.

Senate Democrats were successful in blocking inclusion of one measure, which would have given legal immunity to communications companies that supply subscriber records to the administration’s warrantless surveillance program. Another measure pushed by House Speaker Dennis Hastert, R-Ill., to increase security for courts and judges, also failed to make the final cut, aides said.

But it appeared that the final bill would have a provision, passed by the House, to restrict Internet gambling.

With an eye to the election, Congress has concentrated on security-related issues in the past two weeks.