Politico’s Jonathan Martin tweets, “I got my hands on new Dem internal polling (1/8-1/10) showing Coakley up 50-36 over Brown in Mass SEN. Kennedy gets 6, Undecided 9.”

This is surprisingly in line with what Scott Rasmussen was noticing. Adding this internal poll to the three most recent polls, Coakley comes in with 50 percent, 50 percent, 47 percent, and now 50 percent.

This is much better than the trouble Jon Corzine was in last year, when he hit a ceiling of 42 percent for the better part of a year. But on Election Day, he finished with 44.9 percent. (The idea of a third-party candidate named Joe Kennedy getting 6 percent seems a little high to me – particularly in a cold-weather special election – but we’ll see. In New Jersey, the third-party candidate withered on Election Day.)

But Coakley obviously shouldn’t be high-fiving the staff over polls like this. Turnout in a special election is notoriously tricky to predict, and Massachusetts, cold and miserable for weeks now, is likely to have cold and miserable weather on Election Day with snow a day or two beforehand. That’s a formula to keep any wavering voter at home, and right now, anecdotally, the Republicans have all the enthusiasm and the Democrats are starting to complain on background about Coakley.

That 50 percent or so is probably going to be enough for Coakley, but just barely. Brown’s on a trajectory to make this the closest race in Massachusetts in ages, and the idea of him finishing with more votes is a very real possibility right now.