Baca said the estimated $14 billion merger "will not only maintain an advanced technological innovation, it will bolster the industry, thereby strengthening our economy." "More families and individuals will have an opportunity to access satellite radio," he said.

In his comments, Mack said the proposed union would let satellite radio "become a stronger competitor and will drive all other players in the market, including terrestrial radio, to focus on making their services even more appealing to consumers."

The National Association of Broadcasters is fighting the deal and has gotten support from a growing list of lawmakers. More than 80 members of Congress reportedly have expressed opposition, including Sen. Herb Kohl, a Democrat from Wisconsin and chairman of the Senate Judiciary Antitrust Subcommittee.

House Judiciary Committee Chairman John Conyers, D-Mich., and Rep. Steve Chabot, R-Ohio, also wrote to new Attorney General Michael Mukasey on Tuesday with concerns that Justice officials may "rush through" their analysis of the Sirius, XM merger.

While the two lawmakers have not taken a position on the transaction, they said they are worried that Thomas Barnett, the head of the Justice Department's Antitrust Division, may approve the deal "over the objections of department staff."

"Opposition to this proposed merger is broad and bipartisan because competition is preferable to monopolies," NAB spokesman Dennis Wharton said. "You would have to believe in the Tooth Fairy to accept claims that this would be the first monopoly in world history that leads to lower prices and better service."

The influential Winfrey has her own station called "Oprah & Friends" on XM, and Harpo Productions President Tim Bennett issued a statement backing the merger. Baseball legend Cal Ripken Jr., who hosts an XM show, and General Motors also endorsed the proposed pairing.

A spokeswoman for Sirius and XM said the firms are still hopeful that Justice and the FCC can "make their decisions and the merger could close by year end." "We have fully complied with the requests from both agencies. The ball is now in their court," she said.

Analysts for Stifel Nicolaus said Thursday that a Justice Department ruling "could come any day" and that if the agency approves the transaction, the FCC will follow suit. "We continue to believe it is more likely than not that the DOJ will clear the deal," they wrote.

RBC Capital Markets issued a similar statement, adding that Sirius and XM "shouldn't expect Santa to bring closure" by the end of 2007. The FCC will not be in a position to rule until early February at best, merger watchers said.