A commissioner at the Federal Communications Commission has cast the first vote against the proposed merger between

Sirius Satellite Radio

(SIRI) - Get Report

and

XM Satellite Radio

(XMSR)

, although the deal may already have enough votes to gain approval.

An FCC source confirmed to

TheStreet.com

that Commissioner Michael Copps voted late Monday against allowing Sirius and XM to transfer licenses, verifying an earlier report in

The Wall Street Journal

. The decision does not come as a surprise, as Copps said a month ago that an XM-Sirius deal "is a steep climb for me. I have not pushed for any conditions that would support a finding that the transaction is in the public interest."

Shares of XM, which

posted second-quarter earnings

earlier Tuesday, fell 2.9% to $8.81. Sirius was lately down 4.6% to $2.31.

Copps' decision comes a few short days after Commissioner Jonathan Adelstein, who many thought would also vote against the merger, said he would approve a deal with stricter stipulations than those presented by FCC Chairman Kevin Martin. That leaves the current vote as 2 to 1 in favor of the deal, pending certain concessions from XM and Sirius.

Martin's proposed list of concessions includes a-la-carte pricing, a three-year freeze on price increases, interoperable radios within one year to be compatible with both services, and an open standard for the manufacturing of radio receivers. Additionally, XM and Sirius would have to provide additional public interest channels, and that service would be extended to Puerto Rico, where neither currently offers service.

Adelstein proposed extending price caps to six years after the deal is completed, doubling what Martin is seeking from the two satellite companies. Adelstein also wants 25% of the joined company's spectrum set aside for public interest channels. With about 300 channels currently offered between the two companies, 25% of the combined spectrum would equal about 75 channels.

Additionally, Adelstein says a merged XM-Sirius should be required to disclose technical specifications so that other manufacturers could produce and sell satellite radios, and any new satellite radio receivers subsidized by XM and Sirius would have an open standard that would allow reception of HD Radio broadcasts.

Two FCC commissioners still need to cast their votes. Commissioner Robert McDowell has been rumored to agree with Martin's stipulations, although a formal vote has yet to be cast. Commissioner Deborah Taylor Tate has not publicly commented on her thoughts of the proposed deal.