A just released poll by PPP shows that Elizabeth Warren’s lead in Massachusetts has increased by 4% to 6%:

Warren leads Scott Brown 50-44. The big change over the last month is that Brown’s image is finally starting to take a hit. His approval rating is now a +7 spread at 49/42, down a net 14 points from mid-September when he was at 55/34. There’s an increasing sense that he’s been more a partisan voice for the national Republican Party (45%) than an independent voice for Massachusetts (44%). That’s a 10 point shift from our last poll when voters thought 49/40 that he’d been more of an independent voice.

A Warren surge?  After all, the last PPP poll of this race found Warren up by only 2.

The surge appears to come mostly from an increase in the percentage spread between Democrats and Republicans included in the poll, and in both cases PPP oversamples.  The last poll has a sample of 38% Democrats, and today’s poll has a sample of 41% Democrats.  PPP also decreased the Republican percentage from it’s last poll to this poll from 17% to 16%.

The actual Massachusetts party registratin as of the latest official data was slightly over 35% for Democrats and 12% for Republicans.

But comparing PPP’s polls, Democrats increased by 3% in the sample and Republicans decreased by 1%, and voila, Warren rises by 4%.

It may be that there is an enthusiasm gap or something similar which would justify PPP’s numbers, but they give no explanation.  Since PPP also finds Obama declining (but still comfortably winning), it’s hard to say there is a Democratic enthusiasm surge.

By contrast with PPP which is off on both Democratic and Republican samples, WBUR just released a poll showing Brown up 4% using a sample which follows actual party affiliations.  Pete DaTechGuy has a good explanation of the history of WBUR closely tracking party affiliation.

Warren’s surge appreas to result from an increase in PPP’s increase in the spread between Democrats and Republicans in its sample..  It makes good headlines for Democrats, and it will increase enthusiasm for Warren.  A self-fulfilling prophecy, as so much of polling is these days.

Update:  Stunning PPP poll asks if conservative media wants white people to think Obama  hates them.

And, note this comment by Cassie in the Tip Line:

The chickens are coming home to roost.  Elizabeth Warren’s real tribe – women earning over $100,000 a year – has seen her for what she is and abandoned her.

“Does Elizabeth Warren Have a Wealthy Woman Problem?”