Democratic Sens. Maria Cantwell (Wash.) and Jeanne Shaheen (N.H.) have asked FCC chairman Tom Wheeler to tell the Senate Commerce Committee within 105 days of the successful completion of the spectrum auction whether or not the $1.75 billion TV station repacking fund or 39-month timeline are doable.
Both said they were "uneasy" with the FCC's conclusion that both are doable.
Wheeler has also told Congress that there is flexibility in both if the FCC finds that they are not doable, and he would lead the march back up to Capitol Hill for more money if that is the case.
In their letter, the legislators said they want to insure that consumers' access to local TV is not harmed by the auction.
They said their primary concerns were over the sheer number of variables in the two-sided auction and spectrum repack, something the FCC has never tried before and which has been described as a Rubik's cube of complexity.
Among those variables are the availability of construction equipment, the impact of weather (tall tower work is tough in any weather, more so in the wind and snow), local regulations and availability of personnel.
Then there is the possibility of equipment short-falls—transmitters, antennas—that could inflate the costs and delay the moves.
They also remain concerned about coordination with Mexico and Canada on channel assignments and asked the FCC to get moving with mitigating cross-border interference.