Will radio giant iHeartMedia keep beating in 2017? That’s unclear as the company run by longtime media exec Bob Pittman struggles to refinance $347 million in debt coming due in 2018 — part of the more than $20 billion in borrowings it shoulders.

About half of the holders of the $347 million may reject a refinancing proposal iHeart offered this week, Bloomberg reports.  They want more than the 11.25% in interest the company proposes to pay on the Priority Guarantee Notes that would come due in 2021, replacing current Senior Notes that pay 10.0%.

Last week bond rating firm Moody’s Investors Service dropped its outlook on iHeart to negative from stable due to “the elevated possibility” that it will have to restructure its debt in 2017. Moody’s says that it would “likely” characterize such a move as a “Limited Default.”

It considers iHeart debt speculative with a rating of SGL-4 which makes it way too risky for most banks, colleges, and retirement funds.

About 54% of iHeart’s revenues come from its 850 domestic radio stations. It also has Clear Channel Outdoor, an outdoor ad sales business. iHeart reported a net loss of $402.4 million for the first nine months of 2016, an improvement from the $661.3 million loss in the period last year, on revenues of $4.55 billion, up 0.6%.

The debt weighs heavily at a time when radio broadcasters are losing listeners to streaming services including Pandora and Spotify. That’s put pressure on ad sales: U.S. radio was down 3.1% to $14 billion in 2016, and will drop 3.4% to $13.5 billion in 2017, Magna Global forecasts.

With the challenges to radio, iHeart “will remain poorly positioned to withstand another economic recession or any material weakness in terrestrial radio in the near future,” Moody’s says.

The company — formerly known as Clear Channel Communications —  is groaning under obligations it took on in 2008 when Bain Capital and Thomas H. Lee Partners took it private in a leveraged buyout. Pittman, who helped to create MTV and later became COO of AOL Time Warner, joined  in 2010.

iHeart’s leadership ranks include many names that will be familiar to those who have followed the media business. Former Viacom CFO Richard Bressler is the company’s COO and CFO. MTV cofounder John Sykes is President of Entertainment Enterprises. And the board includes long-time music manager Irving Azoff.