After nearly five months of controversy and debate, members of Congress may face a clear choice over the National Security Agency's program to collect the phone records of nearly every American: endorse it or shut it down.

On Tuesday, lawmakers are expected to introduce the first comprehensive NSA legislation since the disclosure of the agency's phone records program in June. The proposal, from a bipartisan coalition in the House and the Senate, would effectively halt "bulk" records collection under the Patriot Act. Another bipartisan group of lawmakers is preparing legislation that would preserve the program while strengthening privacy protections.

The dueling proposals are setting the stage for what could be a fierce political showdown over the NSA's authorities. NSA Director Keith Alexander and Director of National Intelligence James Clapper ? who are set to testify before Congress on Tuesday ? have defended the phone records program as a vital counterterrorism tool. But privacy advocates and critics on Capitol Hill, led by a diverse group of liberal Democrats and libertarian conservatives, have described it as a gross infringement on civil liberties.