Yglesias gets this exactly right:
[A]s far as domestic issues go, there’s relatively little reason to focus on the fine-grained differences between the different candidates in the primary. If you’re a liberal, the Democrats are all close enough to each other that the differences are bound to be swamped by the distance between what’s proposed and what will actually come out of the legislative process.
It isn’t just that all of the Democratic candidates have very similar health plans (public option, cost control features, private insurance exchange, etc.). It’s that those health plans can change. One of the most revealing parts of Mark Schmitt’s op-ed pleading for candidates to not to get specific on health care was this nugget:
That’s what happened after the Democratic primary-campaign battle over health plans in 1992. Bob Kerrey moved first, taking the left-wing position of support for a single-payer system. Paul Tsongas embraced the centrist, technocratic fix known as managed competition. Under pressure to produce a plan, Bill Clinton half-heartedly wrote one based on the “pay or play” idea, which would require employers either to cover all their workers or pay a tax.
But when Mr. Clinton, as president, unveiled his actual health plan more than a year later, it looked a lot like Mr. Tsongas’s. Meanwhile, Mr. Kerrey forgot his previous embrace of single-payer and became a critic from the right of President Clinton’s Tsongas-like plan.
So it’s entirely possible that Clinton will get elected and push through Obama’s bill. Or vice versa. Or that either of them will go for the whole shebang and work to pass Medicare for All. This doesn’t make them dishonest, or flip-floppers. It just means that they, like all politicians, acknowledge that what makes sense as a campaign proposal and what works in the legislature at the moment are two different things. It isn’t sleazy to be more ambitious because of unusually good circumstances, or more cautious when one is constrained. It’s just good politicking. So picking apart each of the candidates’ plans doesn’t seem like a good way to determine who to vote for, since there’s a non-trivial chance they’ll change anyway.