Grassley has demanded that the FCC release information related to its review of wireless company LightSquared, and has pledged to block President Obama's two FCC nominees over the issue.
Last week, Grassley demanded a meeting with Paul de Sa, chief of the Office of Strategic Planning and Policy Analysis, to discuss the wireless company.
Grassley is the top Republican on the Judiciary Committee, but he does not serve on Commerce, Science and Transportation Committee, which has jurisdiction over the FCC.
LightSquared has invested billions of dollars to launch a nationwide wireless broadband service, but tests have shown its planned network could interfere with GPS devices. The FCC granted the company a conditional waiver last year, but officials say the company will not receive final approval to launch its network until it can demonstrate it has fixed the interference problem.
Grassley and other Republicans have questioned why the FCC allowed LightSquared to get as far as it has in the regulatory process.
LightSquared has accused the GPS industry of mounting a public relations campaign to undermine the company.
--Updated at 8:54 p.m.