(05-24) 04:00 PDT Washington --

Congress headed toward approval of a four-year extension of expiring provisions of the Patriot Act after the Senate voted overwhelmingly Monday to advance the anti-terrorism law over the objections of a coalition of conservatives and liberals.

Because of strong support from the Obama administration, a bipartisan majority in both the House and Senate is expected to ensure passage this week, preventing a lapse of the federal enforcement powers. The provisions expire Friday.

"It is essential to avoid any hiatus in these critical authorities," the White House said in a statement of administration policy.

The law has troubled civil libertarians and conservatives since its enactment after the Sept. 11 attacks. The debate has drawn new interest from the Tea Party movement, whose supporters argue that the law gives the federal government too much authority to spy on terrorism suspects.

Sen. Rand Paul, R-Ky., led opposition to the measure on the Senate floor Monday, arguing that the act allows the federal government to peer too deeply into Americans' private lives. He questioned the wisdom of trading privacy for national security.

"We cannot give up our liberty. If we do, if we trade it for security, we'll have neither," Paul said.

Sen. Dianne Feinstein, D-Calif., who chairs the Senate Intelligence Committee, defended the expiring provisions as tools needed by federal law enforcement to investigate suspected terrorists, especially after the death of Osama bin Laden, when threats may rise.

"This is a time when our vigilance must be heightened," Feinstein said.

The sections of the law expiring Friday include the so-called roving wire tap provision, which allows investigators to continue eavesdropping even when a suspect switches phones.

Another section allows authorities to conduct broad personal records investigations, a provision that has become known as the library records provision. And a so-called lone-wolf provision allows the government to track foreign terror suspects even if they are not linked to a known terrorist group.

In all cases, a court order is required for monitoring.

The Senate voted 74-8 on Monday to advance the bill.

Four Democrats voted no - Sens. Max Baucus and Jon Tester, both of Montana; Mark Begich of Alaska; and Jeff Merkley of Oregon. Bernie Sanders, the Vermont independent, opposed it, along with Republican Sens. Dean Heller of Nevada, Lisa Murkowski of Alaska and Paul.

A final Senate vote is expected later in the week.

Several senators are seeking to amend the bill, and a bipartisan amendment from Paul and Sen. Patrick Leahy, D-Vt., would impose limitations and oversight.