WASHINGTON  As Congress prepares to consider extending crucial provisions of the USA Patriot Act, civil liberties groups and some Democratic lawmakers are gearing up to press for sweeping changes to surveillance laws.

Both the House and the Senate are set to hold their first committee hearings this week on whether to reauthorize three sections of the Patriot Act that expire at the end of this year. The provisions expanded the power of the F.B.I. to seize records and to eavesdrop on phone calls in the course of a counterterrorism investigation.

Laying down a marker ahead of those hearings, a group of senators who support greater privacy protections filed a bill on Thursday that would impose new safeguards on the Patriot Act while tightening restrictions on other surveillance policies. The measure is co-sponsored by nine Democrats and an independent.

Days before, the Obama administration called on Congress to reauthorize the three expiring Patriot Act provisions in a letter from Ronald Weich, assistant attorney general for legislative affairs. At the same time, he expressed a cautious open mind about imposing new surveillance restrictions as part of the legislative package.