Federal Bureau of Investigation Director James Comey told Congress this week it’s too soon to tell if surveillance reforms recently enacted by Congress will hinder federal investigators’ efforts to prevent terrorism, but he expects the new program for accessing Americans’ phone records will work as well or better than the original.

Comey told the Senate Judiciary Committee Wednesday the FBI doesn’t yet know if shutting down the National Security Agency’s phone metadata collection program will have a negative impact on national security, but he expects it won’t.

“In theory it should work as well or better than what we used to have,” Comey said. “But I don’t know yet.”

The previous program, charged with collecting virtually all Americans’ landline telephone records, likely some wireless records and storing them in a single government database for five years, was shuttered at the end of November in place of a new framework approved by Congress via the U.S.A. Freedom Act in May.

Under the new program, telephone providers themselves store records for two years, and require the signals intelligence agency to get a Foreign Intelligence Surveillance Court order to acquire specific records based on predefined search terms, and narrow the number of results.

Director of the NSA Adm. Mike Rogers told Congress earlier this fall the new program strips his office of emergency powers to access records immediately in the event of a national security crisis, and will slow the agency down and reduce its effectiveness in responding to terrorist threats.

In response to questions from the Senate Intelligence Committee, Rogers said unequivocally the new program would reduce the NSA’s operational capability, and hinder its ability to act in the event of a 9/11-style attack.

“Not in minutes,” Rogers said on how quickly his agency could respond to such a threat. “I doubt we could do it in minutes.”

RELATED: Rogers: New Phone Metadata Program Will Make NSA Slower, Less Effective

Florida senator and 2016 GOP candidate Marco Rubio said last weekend the program is already hampering law enforcement, and cited a recent Associated Press report claiming federal investigators were only able to access the two years-worth of records belonging to San Bernardino attackers Tashfeen Malik and Syed Farook.

“Just four days before the terrorist attack in California this week, the U.S.A. Freedom Act limited our access to critical information about potential threats,” Rubio said. “Because too many in Washington have failed to grasp the nature of this enemy, we have less access to intelligence information now than we did just days ago.”

Comey declined to say whether the investigation was inhibited by the new program.

“I don’t want to talk about particular techniques we’re using to understand that attack,” Comey told senators. “I need not to talk about it in the context of that.”

Utah Republican and Freedom Act chief sponsor Sen. Mike Lee said during Wednesday’s hearing the allegations by Rubio and others are highly unlikely, since the Freedom Act preserved the last five years of records in the six-month interim between Congress’ passage and the NSA’s implementation of the new framework.

“It is significant that only four days prior to the attack, the government had access to all of the records that it had access to for years prior to the passage of the U.S.A. Freedom Act, because there was a six-month moratorium between its passage and it kicking in,” Lee said.

A frequent ally of Texas Republican and 2016 GOP candidate Sen. Ted Cruz, Lee took the opportunity to clarify the new program allows the government to ascertain the same types of records it kept before the old program expired, and counter the narrative touted by Rubio that Cruz and others who supported the NSA reform bill are weak on national security.

“I personally consider that highly unlikely, some would say mathematically impossible, that it had any difference,” Lee said.

The two-year span covers the entire duration of Pakistani native Tashfeen Malik’s residency in the U.S., including she and American Syed Farook’s marriage in August 2014 and after. Tashfeen and Farook met in Saudi Arabia in 2013, but were radicalized years before, Comey told lawmakers Wednesday.

That hasn’t stopped Rubio from joining with Arkansas Republican Sen. Tom Cotton on a bill that would walk back select NSA reforms, while making permanent broader Internet surveillance authorities allowing the signals intelligence agency to view the actual content of online communications – including, in some cases, those of Americans.

RELATED: Senate Bill Would Stall NSA Reforms, Make Spying Powers Permanent

Though weighing a policy shift on the issue of government access to encrypted communications – the focus of Wednesday’s hearing – the White House isn’t backing away from the Freedom Act program, endorsed by the Obama administration last year.

RELATED: Feinstein Working on Legislation to ‘Pierce’ Encryption

“I do think it’s still too early to make any grand pronouncements about what could have been done differently to prevent this terrorist attack from occurring,” White House Press Secretary Josh Earnest said Wednesday.

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