Ben Adler doesn’t think the Iraq war should be one. While he opposes it himself, he thinks a progressive argument can be made for it. He isn’t against litmus tests on principle, though:
What are examples of better issues for Democratic litmus tests? I think of voting rights and stem-cell research. Voting rights are fundamental to American democracy, and, in the abstract at least, they are a settled issue in the eyes of the public — no Democrat can claim he or she would lose a seat by standing up for them. Similarly, with stem-cell research, there is no credible progressive argument against it and it has the potential to cure diseases that claim more than a thousand times as many American victims as has the Iraq War. (It’s a question worth asking why significant numbers of liberal activists are beginning to identify Iraq as a litmus test issue while Senator Ben Nelson of Nebraska gets a pass on his opposition to stem-cell research.)
I’m not sure what Adler wants to do with Democrats such as Nelson–run primary campaigns against them? But I don’t think this would work too well. For one thing, 14 House Democrats voted to sustain the president’s veto of funding for embryo-killing research. Most of them are from socially conservative districts. It may be that the research funding is sufficiently popular that they could win in those districts even as supporters of the funding. But it’s not so popular that you could run a successful primary campaign against them based solely on that issue. But a primary campaign based on a broader critique of these Democrats would run the risk of handing the nomination to a liberal Democrat who can’t win the district.
And there’s another problem. If opponents of cloning are defined as opponents of stem-cell research for Adler’s purposes, the number of Democratic dissenters gets bigger. In 2003, 42 House Democrats voted for a comprehensive cloning ban. Should they all be purged? That’s not going to do much to help Nancy Pelosi become Speaker.