FCC staffers report to the chairman, so the two vacancies are unlikely to prevent the agency from going about its daily work.
"If anything, things might operate a little more quickly because there are fewer offices to check off on things," Schwartzman said.
The agency does not compile data on the number of commissioners serving at any given time, but Schwartzman said he believes the last time the commission had only three members was for a several-month period in the early 1990s.
Harold Feld, legal director of advocacy group Public Knowledge, said the political dynamic on the commission would remain the same with or without Obama's nominees.
The commission is made up of two Democrats, Chairman Julius Genachowski and Mignon Clyburn, and one Republican, Robert McDowell. By law, only three commissioners can be from the same party, and President Obama has nominated one Democrat and one Republican.
Feld also said the vacancies will mean "less room for the backroom negotiating."
With only three commissioners, Chairman Genachowski would only need to win the support of one of the other members to push through a policy.
The FCC is not expected to take up any particularly contentious or partisan issues in the next several months. Pending issues include Verizon's spectrum deal with a group of cable companies and an update of media ownership rules.
Obama's FCC nominees are considered uncontroversial, but Grassley has said he will block their nominations until the agency releases internal documents related to its review of wireless company LightSquared.
Tests have shown the wireless broadband company's network could interfere with GPS devices, and Grassley questions whether the FCC has shown inappropriate favoritism to the company.
FCC officials say they will not give LightSquared final approval to launch its network until it resolves the interference problem.