Coattails and the Senate: An Update

A November 10 post asked whether President Obama's coattails were responsible for the Senate Democrats' net gain of two seats. It looked the 11 Democratic victories in races that RealClearPolitics rated as "tossups" or "leans," comparing the percentage of the vote for the winning Senate candidate and President Obama.  Below is an updated version of the table, with final, certified figures.  As before, it shows that only in Connecticut, Massachusetts, and Wisconsin did the president get a higher percentage of the vote than the winning Senate candidate, and only in Massachusetts was the difference more than five percent.  We have to conclude that the evidence for any coattail effect is very weak.

	Winner	Winner%		Obama%
Connecticut	Murphy	55.2%		58.1%
Florida	Nelson	55.2%		50.0%
Indiana	Donnelly	50.0%		43.9%
Massachusetts	Warren	53.3%		60.7%
Missouri	McCaskill	54.8%		44.4%
Montana	Tester	48.6%		41.7%
North Dakota	Heitkamp	50.5%		38.7%
Ohio	Brown	50.7%		50.7%
Pennsylvania	Casey	53.7%		52.0%
Virginia	Kaine	52.9%		51.2%
Wisconsin	Baldwin	51.5%		52.8%

(In the Ohio race, rounding to two decimal places instead of one shows that Senator Sherrod Brown got a slightly greater share of the vote than President Obama: 50.70 percent to 50.67 percent.)