Via Legal Insurrection, the show starts at 7 p.m. ET. Why should you watch if you’re not from Mass? Two reasons. One: Obviously, we’re all interested in seeing how a moderate Massachusetts Republican fares in a debate against a prominent “you didn’t build that” liberal. Consider this an undercard for the main event on October 3, with the important caveat that Scott Brown’s free to tack much further to the left tonight than Romney will be a few weeks from now. Two: The GOP’s hopes of retaking the Senate have been fading for weeks and not just because of Todd Akin. A quick tour of RCP’s poll of polls reveals Democratic candidates leading by four points in Virginia, by seven in Ohio, by eight in Florida and New Mexico, and by nearly 10 in Michigan. (Akin trails McCaskill by five in Missouri.) At the moment, Wisconsin, Montana, and even Nevada all appear to be toss-ups. Losing a seat in Massachusetts that’s already red will make things that much harder, never mind the fact that it would mean sending Fauxcahontas, the left’s new hero, to the Senate.

The good news is that today’s Boston Herald poll has Brown up four points. The bad news is that that’s the only poll taken over the past month that has him ahead. Warren appears to have gotten a bit of a bounce after the convention and leads in other recent surveys by anywhere from two to six points. Frankly, it’s amazing that he’s even this close: In a presidential election year, in a state this blue, he’d need a ton of ticket-splitting to keep this seat — and yet, thanks to his own likability, some careful political positioning as a de facto independent, and Warren’s lackluster campaign and personal “meh”-ness, he’s right in the thick of it. If he ends up losing, it won’t be because he failed to do what he needed to win. It’ll be remorseless partisan demographics at work.

Looks like the debate will be airing on both C-SPAN 3 and at CBSBoston.com. Click the image below to watch.