That's how the American Heritage Dictionary of the English Language defines "litmus test" when it's used as a political metaphor (emphasis mine).
That makes no difference to MSNBC's Andrea Mitchell and Joe Scarborough, who see a new "litmus test" for the GOP developing out of the New York 23rd Congressional District special election.
Scarborough, appearing with Mitchell on MSNBC shortly after 1:15 p.m. EST, slammed potential 2012 presidential hopeful Gov. Tim Pawlenty (R-Minn.) for arguing earlier today on his "Morning Joe" program that there's no room in the GOP for what may be called "Dede Scozzafava Republicans" who are far [left] afield from the Republican mainstream.
Pawlenty made clear that what deep-sixed Scozzafava with conservatives was not one or two issues, but the totality of her stands on issues, which were decidedly left-of-center on economic and social matters. Nonetheless, Scarborough and Mitchell agreed that Pawlenty was instituting a "litmus test" which would hurt the Republican Party in the future.
Scarborough, a former Republican congressman, even drew the Reagan card on Pawlenty, seeking to paint the Minnesota governor as a violator of the Eleventh Commandment.
Here's the transcript of the video portion embedded above (audio available here):
ANDREA MITCHELL: Let me play a little bit of your conversation with Tim Pawlenty, because it was so telling.
Gov. TIM PAWLENTY (R-Minn.) on the Nov. 3 "Morning Joe": If Olympia Snowe disagrees with us on one or two things, there room for her? Of course. There is a range of behavior and issue positions we can accept and celebrate in the party, and there's room for all of that. But you can't be so far out of that range that you become Dede Scozzafava.
MITCHELL: So he's applying a litmus test. You kept going after him and after him and he is sticking to a litmus test as to who can be a Republican, ignoring what part of the country they're from. That doesn't make any sense.
JOE SCARBOROUGH: Yeah, I mean, let's get this straight. We got the guy from Mississippi saying we'll take moderates in Maine. We got the guy from Minnesota saying "No, I've got a litmus test you have to follow or else you're not a member of my party." I think in this case, let's hand it to the open-mindedness of our Mississippi native, Haley Barbour, because he's exactly right. He understood what Ronald Reagan understood.
SCARBOROUGH: And that is, remember Reagan in '76? He asks Schweiker, one of the most liberal Republicans in the Senate, from Pennsylvania, to be his running mate in '76. He said, "If I win, I'm going to have Schweiker with me." That's something, with all due respect to Tim Pawlenty, didn't sound like he got this morning.