WBUR Poll Shows Which Voting Blocs Have Shifted Toward Baker

The final WBUR Tracking Poll shows Republican Charlie Baker with a single-point lead over Democrat Martha Coakley in the race for governor. Our first tracking poll, released before the primary, showed Coakley up 7 over Baker in a then-hypothetical match-up. Our polling shows that Coakley's support has stayed mostly flat since then, while Baker has climbed up to meet her.

So how did Baker make up the gap? There are a few ways to slice this. Voters prefer Baker over Coakley on the most important issues in the race -- the economy and managing state government. Baker and supportive outside groups have also raised and spent more money spreading their message and defining Coakley. At the same time, Baker was able to redefine himself, helped in part by voters mostly forgetting about him since his last run for governor, in 2010. And Baker has cut into Coakley’s margin in cities like Boston, which have driven Democratic victories in recent statewide elections.

These are all important plot lines, but how are they playing with the audience — the voters? To find out, we've combined the nine tracking polls we have done — over 4,700 interviews — into four chronological sets. This grouping gives us a large enough sample to analyze smaller slices of the electorate while still showing a trend over time.

The visualization below shows the results. Along the left are nearly 40 demographic groups, sorted in order from largest margin for Charlie Baker to largest for Martha Coakley. The color and size of the boxes next to each indicates by how much that group is going for Baker (red) or Coakley (blue) in that set of polls. Mouse over a box to see the actual number, and also to bring up a detailed trend line of Coakley and Baker’s support (without leaners) across the entire Tracking Poll. The thickness of the lines in the chart corresponds to the demographic's share of the poll sample (and, by extension, the electorate).

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The top and bottom of the table show pretty much what you might expect. Republicans, men and wealthier voters have been in Baker’s camp since the beginning, as have Democrats, women, non-white voters and younger, less affluent, more urban types for Coakley. The difference is that Baker has kept and grown his margins with most of his demographics, while Coakley has not. In the case of women voters, for example, her lead has dropped from 18 points in the first set of polls to 11 in the last set. With women playing a key role in recent Democratic victories, this narrower margin is a troubling sign.

In fact, over the course of the WBUR Tracking Poll, nearly every demographic has shifted towards Baker to some degree. This is partially related to his entrance into the race as an unknown quantity, while Coakley was already a familiar face to nearly all voters. Coakley still leads among her core groups — Democrats, women and non-white voters — but has lost ground with many of them. Baker, meanwhile, has consolidated and grown leads with key groups. For instance, he led the all-important unenrolled voter bloc by 6 points at the start of the Tracking Poll and now carries them by 21.

The middle of the table is the real battleground: groups the two candidates are fighting to win over. Even there however, Baker has made up more ground. The groups that have flipped from blue to red over the course of the poll include some large and central demographics: white voters, college graduates, voters in the middle of the income and educational strata, and female voters who are neither Democrats nor Republicans. Meanwhile, there’s not a single group that has flipped from red to blue over the course of the poll.

All this suggests momentum for Baker. But since he was starting from behind, these gains have only brought him level with Coakley, according to our final poll. It is perhaps indicative of Massachusetts' partisan leanings that a Republican candidate with momentum, better favorables and far more money has only drawn even. Depending on Coakley's final number among Democrats, Baker may have to do even better than 21 points among unenrolled voters to win.

Given that past polls have tended to underestimate Democratic support slightly, there’s still a good chance that Coakley and the Democrats can squeak out a win. If they do, though, it will be by stopping the wave just before it crashes over the wall.