For the first time Democrat Elizabeth Warren is polling narrowly ahead of incumbent Republican Sen. Scott Brown in the Massachusetts senate race. From PPP:

Elizabeth Warren has had an incredibly successful launch to her Senate campaign and actually leads Scott Brown now by a 46-44 margin, erasing what was a 15 point deficit the last time we polled the state in early June. [...]

The surprising movement toward Warren has a lot to do with her but it also has a lot to do with Scott Brown.  We now find a slight plurality of voters in the state disapproving of him- 45%, compared to only 44% approving.  We have seen a steady decline in Brown’s numbers over the last 9 months.  In early December his approval was a +24 spread at 53/29.  By June it had declined to a +12 spread at a 48/36.  And now it’s continued that fall to its current place.

While it is still early and a lot can change between now and November 2012, this is big news both in Massachusetts and nationally.

Despite Massachusetts being extremely blue, only a few months ago Scott Brown appeared to be in very good re-election shape due to his personal popularity and moderate image. This poll indicates Brown is beatable, which should encourage a lot of money from both sides to pour into this race.

The new closeness of this race could have big national implications. Democrats will have 23 seats to defend this cycle compared to the Republicans who only need to defend 10 seats. A Democratic win in Massachusetts could help make up for likely Democratic losses elsewhere, like in North Dakota. It is easy to picture a scenario where the outcome in Massachusetts is the difference between Democrats narrowly holding onto the Senate and narrowly losing the chamber.