Sirius XM said in a press release that it has exchanged $172.5 million of existing convertible senior notes due in December for new senior secured notes now due in June 2011. Before the transaction, $400 million of the senior notes were set to mature in December, leaving approximately $227.5 million in senior notes outstanding.

The company said the exchange is part of a “larger restructuring effort,” which has created a whirlwind of speculation in previous days about Sirius XM’s viability. Sirius XM confirmed it was in discussions with other parties regarding transactions that could refinance some of the company’s and its subsidiaries’ debt.

“These transactions may not be successfully consummated,” the company said in the release. “If these transactions are not consummated, it may be forced to file for bankruptcy protection as early as February 17, 2009.”

With few days remaining until a chunk of the company’s approximately $3.2 billion in debt will come due, Sirius XM is in a very tough spot. While staring down a potential bankruptcy protection deadline, Sirius XM and its CEO Mel Karmazin has been working to thwart an attempt by EchoStar (SATS Quote – Cramer on SATS – Stock Picks) and its CEO Charles Ergen to take control of the company.