Who is the GOP Base that wants Medicare killed?

To my 2½ readers, amongst whom may be ½ or 1 who is tired of hearing about Medicare-Killing Republicans, I apologize and suggest skipping this post.

I find this, from an article in Salon, virtually incomprehensible:

From a general election standpoint, last month's vote [in the House, to turn Medicare into a coupon to buy private health insurance, which would probably be unavailable at any price anyway] ...was potentially suicidal for the GOP brand and for individual House incumbents in competitive districts. But from a primary election standpoint, it was potentially helpful -- if not necessary -- for the survival of all of the GOP lawmakers who backed it. As we saw in last year's primaries, the Republican Party base in the Obama era is a restive bunch, unimpressed with incumbency and establishment credentials and vigilant against sellouts. The Medicare overhaul, which would replace the current program with vouchers that could be used to purchase private coverage, represents precisely the type of legislation that the GOP base now insists its elected officials embrace.

 Who is this supposed "GOP base?"  It appeared to me from the coverage of Town Halls and such, as well as some hard data from polling, that even the Tea Partiers are opposed to  this plutocratic idea that really only benefits those too rich to care about Medicare. Hell, as I noted the report here, even health insurers oppose turning Medicare into a coupon: they know they can't profitably sell insurance for the value of the coupon, but would end up with a huge mess on their hands if the over-65 population were suddenly mostly uninsured.

So, as I say, this makes no sense whatsoever. But, to the extent the Repubs have committed to a suicide pact over Medicare, and it makes it that much easier to replace a good number of them with Democrats in '12, I say Hallelujah and Om Ah Hum.