If Democrats lose all seven of these seats in Romney states, and if Republicans avoid nominating candidates who manage to lose seats that currently seem unloseable, Republicans will have at least a 52-48 Senate majority.

And they have at least an outside chance of winning seats in 2012 target states Colorado, Iowa and New Hampshire, plus Michigan.

Well, you might ask, isn’t it unusual for parties to sweep all the close races? Actually, sometimes they do.

Republicans did in 1980 and Democrats did in 1986 — and those were the same seats.

Republicans won the bulk of close races in 2002, and Democrats won the bulk of close races in 2008 — the same seats again and the ones up next year.

A sweep is by no means certain this time. But if the Obamacare rollout is a “train wreck,” as Baucus feared, the odds get better.