Legislation which changed the Foreign Intelligence Surveillance Act (FISA) to give U.S. telecoms immunity from prosecution for participating in legally-ambiguous spying programs, isn't set to expire until 2012 -- but one group of U.S. Senators appears to see opportunity in crisis.

Amid the calamitous debt-limit talks seizing Washington in recent weeks, the Senate Select Committee on Intelligence kick started yesterday the mark-up of legislation that would reapprove the spying activities and telecom immunity.

While the Obama administration has urged the FAA's renewal, at least two Senators are calling for greater caution in the process. Sens. Ron Wyden (D-OR) and Mark Udall (D-CO) asked the director of national intelligence to explain how the Obama administration had applied the 2008 act, and to provide an estimate of how many Americans' communications were spied upon.

The administration refused to provide an estimate, according to The Associated Press.

"Congress needs to know if the laws it writes are being interpreted and implemented as intended before it is asked to extend them, and failing to assure the public that government agencies aren't violating the rights of law-abiding Americans erodes public confidence and makes it harder for intelligence agencies to do their jobs," Sen. Wyden said in a statement released Thursday.

The senators also sought information earlier this month on how U.S. spy agencies and telecoms are handling geolocation data from mobile phones, which allows authorities to track virtually anyone they wish.

Above all, they called for an "informed debate" of the FISA Amendments Act ahead of reapproval, but that seems unlikely.

Wyden was one of the most prominent critics of the FISA Amendments Act before it passed in 2008, effectively legalizing warrentless wiretapping. Then-Sen. Barack Obama (D-Ill.) had pledged to oppose the act as well, but ultimately changed his mind just before the vote was taken. His administration has continued the Bush-era policies on wiretapping.

Republicans, in large part, favored the bill, which protected the prior Republican administration and its accomplices from potential legal action in what appeared to be clear violations of the prior FISA Act.

FISA was established in the wake of the Nixon-era spying crisis, where the administration had wiretapped its political opponents to gain an upper-hand. It established a secret court that could approve warrants for spying operations even after they'd begun, but the Bush administration argued that authority wasn't adequate to combat modern threats in an increasingly connected world.

The amended FISA essentially gave law enforcement and intelligence agencies blanket authority to wiretap anyone, so long as one party to the communications is "reasonably believed" to be outside the country.