AT&T’s vice president of federal regulatory affairs Joan Marsh said the 39-month transition period for broadcasters that will follow the upcoming FCC spectrum auction will be an “enormous lift” and warned that a more realistic timeframe may need to be considered.

According to a Bloomberg BNA report, Marsh’s comments came Tuesday during a panel at the Americas Spectrum Management Conference.

Marsh said there is “nothing in the record” to support the 39-month transition timeframe adopted by the FCC and said the nearly 850 TV stations that will likely need to move may need more time.

Marsh said AT&T is looking to get a better picture of when it will gain access to spectrum won in the auction, and noted that even planning for a very efficient transition would mean embracing a more “realistic expectation.”

The 39-month transition period was adopted by the FCC in May 2014, along with other rules governing the upcoming auction.

According to the FCC, broadcasters willingly participating in the auction with have 39 months from the start of the repacking process to clear their spectrum. Broadcasters will need to cease operations, move from UHF to VHF, or share a different channel, the FCC said.

The repacking rules drew the ire of the National Association of Broadcasters, which subsequently lobbied for a longer repacking period, but have been celebrated by wireless carriers looking to access the spectrum in a quicker timeframe.