Coattail Effect: How far can a Governor's job approval carry his or her party's presidential nominee?

Governor Bob McDonnell (R) (left) has an enviable 51/29% job approval rating back home in Virginia, yet the Republican candidate for President lost to the President by 3 points. Meanwhile, Wisconsin GOP Governor Scott Walker (right) had a decent 51/46% job rating, yet Romney lost his state by 7 points.

Virginia Governor Bob McDonnell became one of the most prolific campaign surrogates in the 2012 election, crisscrossing the country on Mitt Romney's behalf. Not only was he a popular home-state Governor, but he just happened to be the chief executive of one of the most hotly contested swing-states in the nation. That's a helpful combination to have around. While popular Republican governor's like Chris Christie and Susana Martinez were good faces to have associated with the Romney campaign, their home-states of New Jersey and New Mexico were never really in contention. They didn't pack the same one-two punch of Virginia's Bob McDonnell.

Obviously, there's a reason we seldom saw or heard of Florida Governor Rick Scott barnstorming across the state with Mitt Romney, or Pennsylvania Governor Tom Corbett holding local town-halls with Paul Ryan. Both of them averaged 39/45% and 35/46% job approval/disapproval ratings respectively in the final two months of the campaign.

But does the actual evidence suggest that a Governor's job approval/disapproval rating can affect Presidential election results on a state level? Unfortunately, the data is not terribly clear.
The table below contains a lot of information, so let's break it down piece by piece. It compares the job approval/disapproval ratings for every U.S. governor over the final two months of the 2012 Presidential campaign to actual election results, as well as actual election results to Obama/Romney's favorable/unfavorable ratings. In order for a particular state Governor to be included in the chart, he or she must have had at least one job approval assessment in the September and October before the election. That's why a few Governors, like Alabama, Mississppi, Wyoming, etc are missing. Red entries indicate either a Republican Governor, a Republican election win, or a net state-based positive favorability rating for Mitt Romney in the presidential election. Likewise, blue entries indicate Democratic Governors, a Democratic election win, or a net state-based positive favorability rating for Barack Obama. Since exit polling was only conducted in 31 states in 2012, not every state will include an Obama/Romney favorability assessment. Polling information was compiled from tpm poll tracker, pollster, and various internet searches:

For an easier to read, larger version of the above table, click here.

Of the top 10 most popular Governors in the country (based on polling averages taken from September 1-November 6 2012), 5 were Democrats, and 5 were Republicans, in 5 blue states, and 5 red states. Of the 10 least popular, 5 were Democrats, 4 Republicans, and 1 liberal Independent, in 9 blue states, and 1 red state. This stat seems to suggest red-state residents (those states that voted for Romney in the last election) tend to be bigger fans of their Governors (whether they be Democrats or Republicans) than blue state residents.

In order to better compare average gubernatorial job approval ratings to state-by-state election results, the data from the above table has been placed into the bar graph below:

For an easier to read, larger version of the above chart, click here.

Now you can see why the data is unclear as to exactly how much of a correlation there is between gubernatorial job approval ratings and his or her party's presidential election results in that state.

Sometimes, such as in the case of Andrew Cuomo (D) in New York, Deval Patrick (D) in Massachusetts, Rick Scott (R) in Florida, or Paul LePage (R) in Maine, the correlation is somewhat strong.

Other times, there is no correlation at all (see Mike Beebe (D) in Arkansas, Steve Beshear (D) in Kentucky, Susana Martinez (R) in New Mexico, Brian Sandoval (R) in Nevada, Neil Abercrombie (D) in Hawaii, or Chris Christie (R) in New Jersey).

One thing is clear however; the correlation is not strong enough to warrant it as highly predictive. There are  far too many occurrences of their being very large gaps between the Governor's approval rating and his/her party's presidential election result.

The largest such gap is seen in Arkansas. While Arkansas has become deeply Republican over the last two presidential election cycles, their Democratic Governor Mike Beebe remained quite strong in the final two months of the presidential election. Over 2/3 of Arkansans approved of the job he was doing, with less than 1 in 5 disapproving. But despite Beebe's 68% approval rating, Democratic President Barack Obama only managed to win 37% of the vote, to Mitt Romney's 61%.

The smallest gap between gubernatorial job approval and election result in 2012 was in New York, where Mario Cuomo's average net +31 point job approval rating closely mirrored President Obama's 27 point victory over Mitt Romney in the state.

But to put it simply, you probably wouldn't want to place any bets on state presidential outcomes based on the Governor's job approval rating, as it appears that even highly popular governors can have very limited coattails. Your money would, however, be much better spent placing your bet based on presidential favorability ratings:

Unlike gubernatorial job ratings, Barack Obama's state-based net favorability rating seemed to be a strong predictor of election results, especially in comparison. Obama performed well in the states where his favorability rating tended to be more positive, and worse where it was negative.

Note: Oddly enough, in Arizona, Barack Obama lost the state by 10 points, despite having a positive favorability rating of, you guessed it, 10 points (54/44%).  That means there was a fair-sized chunk of Arizona voters that personally liked the President, yet voted for Romney nonetheless.