The Federal Communications Commission said petitions to deny the application are due by Nov. 1. Responses to those filings are due two weeks later, with a final rebuttal to the responses by Nov. 20.
The FCC is looking into Liberty's proposed takeover of Sirius, in which Liberty already has amassed the equivalent of a 47.3 percent stake. If the commission approves, Liberty has said it will buy up enough shares within 60 days to give it majority control.
Liberty saved Sirius XM from near-bankruptcy in February 2009 by agreeing to lend it up to $530 million in exchange for preferred stock that amounted to a 40 percent stake.
Since then, Sirius recovered from its tailspin and as of the end of June it had more than 22 million subscribers.
Sirius shares rose 7 cents, or 2.7 percent, to $2.64 in afternoon trading. Liberty Media shares were up 34 cents at $105.11.