It's been a week of strong signals for satellite radio.
The deal got the support of Reed Hundt, who was chairman of the Federal Communications Commission when the two companies received licenses -- on the condition that they remain separate.
On Wednesday, billionaire investor George Soros reported in a regulatory filing that his fund had taken large stakes in both XM and Sirius.
XM Chairman Gary Parsons is hopeful about federal regulatory approval of the deal, which includes a variety of pricing plans based on the listening choices of subscribers.
"By combining the two companies, we get additional programming: Sirius has the NFL, XM has Major League Baseball; XM has Oprah, and Sirius has Howard Stern," he told CNBC.
Parsons also pledged "lower-priced opportunities" for subscribers who don't want the combined package.
The merger still needs the blessings of the Justice Department and the FCC.
FCC Chairman Kevin Martin has been a strong advocate of "a la carte pricing" by cable television providers. Parsons says the merger plan promises that -- and more.
"We offer a number of different packages: A music-only package, or a package that's family-friendly, so there's no adult content on there, and yet it's a lower price," Parsons said.
He insists a merger is not simply a means to financial survival. "We both believe that we have a business that can be successful on its own," Parsons said. "Actually, we will strengthen competition because we compete with the terrestrial radio industry and others by putting a better product out there."
In addition to terrestrial radio, Sirius and XM have argued that they face competition from such media as Apple's iPod, Internet radio and smart phones.