Senate Republicans blocked Majority Leader Harry Reid's attempt Tuesday to extend the life of a surveillance law due to expire Feb. 1, raising the stakes for a vote expected later this week on a new version of the law.

Reid, D-Nev., failed to get the unanimous consent he sought to extend the Protect America Act, which Congress hastily adopted last summer in the face of warnings from Bush administration officials about dangerous gaps in the government's ability to eavesdrop on terrorist e-mails and phone calls.

Senate Minority Leader Mitch McConnell, R-Ky., objected to the extension, saying there was enough time before the law expires to pass a longer-term renewal of the government's terrorist surveillance authority.

Reid plans to bring to the Senate floor on Thursday competing versions of an update to the Foreign Intelligence Surveillance Act. If a bill is not approved then, Reid said he would require the Senate to work through the weekend to a bill passed.

The original FISA law requires the government to get permission from a special court to listen in on the phone calls and e-mails of people in the United States. Changes in communications technology mean many purely foreign to foreign communications now pass through the United States and therefore require the government to get court orders to intercept them.

The Protect America Act, adopted in August, eased that restriction. Privacy and civil liberties advocates say it went too far, giving the government far more power to eavesdrop on American communications without court oversight.