Senator Chuck Grassley, a vocal critic of the FCC's handling of LightSquared, says he will continue to bar two FCC nominees from being confirmed despite the agency's decision to block LightSquared's network.

The FCC said Tuesday it would void LightSquared's original waiver for a hybrid satellite-terrestrial LTE network and indefinitely suspend its ancillary terrestrial component authority, which allowed it to deploy base stations on the ground in addition to its satellite operations.

A spokeswoman for the Iowa Republican said Grassley will continue his hold on the nominees until the FCC fesses up to why it granted LightSquared a conditional waiver for an LTE network in satellite spectrum last January despite the NTIA's concerns about GPS interference.

"The agency put this project on a fast track for approval with what appears to have been completely inadequate technical research. After all of this time and expense, still no one outside of the agency knows why," Grassley said. "If we don't find out how and why the FCC failed to avoid this controversy, then it will keep operating as a closed shop instead of the open, publicly accountable agency it should be."

The FCC will operate with just three acting commissioners until nominees Jessica Rosenworcel and Ajit Pai are approved. Grassley's objection is the primary barrier to their instatement, as both Rosenworcel and Pai have received broad bipartisan support. The ban could be surmounted by a cloture motion from Senate majority leader Harry Reid.

FCC officials have repeatedly declined to meet with Grassley. The agency sometimes ignores lawmakers' requests unless they are made by the heads of the House Energy and Commerce Committee or the Senate Commerce, Science and Transportation Committee, which have jurisdiction over the FCC.

Grassley is the ranking Republican member of the Democrat-controlled Senate Judiciary Committee but does not hold a seat on the Senate Commerce and Transportation Committee.

Grassley claimed last month that LightSquared's main backer, Philip Falcone's hedge fund Harbinger Capital Partners, tried to bribe him into backing off his inquiry.

LightSquared has denied the allegations.

LightSquared has not issued any statements after the FCC announced its decision but maintained in earlier comments that it "remains committed to finding a resolution with the federal government and the GPS industry."