Think Progress gets its hands on an internal memo from Premiere Radio Networks that lists nearly 100 national companies that have asked that their advertisements not be played on the Rush Limbaugh show — companies that have not been publicly named until now. Think Progress claims that brings the total of sponsors who have pulled out in the wake of the “slut” controversy to 141 — far more than previously thought.

I’ve confirmed the authenticity of the memo with a spokesperson for Premiere, home to Rush’s show. It’s unclear for now what exactly it means. The spokesperson, Rachel Nelson, emails:

This is a routine communication that notifies our affiliates’ traffic managers of advertisers that prefer not to be in ANY potentially controversial programs. It is prepared and disseminated on a quarterly basis.

That appears to mean that nearly 100 advertisers asked for their ads not to be included on any “controversial” show, Limbaugh’s included.

And indeed the memo does say this of those advertisers: “They’ve speifically asked that you schedule their commercials in dayparts or programs free of content you know are deemed to be offensive or controversial (for example, Mark Levin, Rush Limbaugh, Tom Leykis, Michael Savage, Glenn Beck, Hannity). Those are defined as environments likely to stir negative sentiment from a very small percentage of the listening public.”

What’s unclear is whether this is a direct reaction to the Limbaugh controversy. Nearly 100 major advertisers are asking to be excluded from these shows. That hardly seems routine. The question now is whether anything like this has happened before and whether these companies previously were okay advertising on these shows, before the “slut” controversy broke out.

Nelson didn’t respond to repeated requests for a follow interview so I could get clarification on these points.

Premiere has defended Limbaugh’s right to controversial opinions and said that his apology was sufficient. But this memo raises at least the possibility that Limbaugh is on the verge of losing far more advertisers than previously thought, though more clarification is in order. More when I learn it.

*****************************************

UPDATE: Ultra Violet, a group that organizes around issues important to women and has launched a campaign to pressure advertisers to drop Limbaugh, is up with a new ad on D.C. cable pressing the issue on Mitt Romney.