By Jim Ellis
Dec. 13, 2018 — Reviewing documentation from the 2018 US Senate races, it appears there is at least a tangential correlation between an incumbent senator’s pre-campaign approval rating and the vote percentage garnered on Election Day.The Morning Consult public affairs firm routinely surveys senators and governors to produce approval indexes for every member. Their 3rd Quarter 2018 sampling was publicly released on Oct. 10, one month before the election and just at the beginning of prime time campaigning.
Looking at the 32 incumbent senators who were on the ballot in November, the mean average increase from the individual’s approval score to the final vote percentage is 9.6 points when using the Morning Consult favorability index as our constant and the median is nine points.
The senator dropping the furthest from approval to vote percentage, down five points, was Maine Sen. Angus King (I), but the number is a bit deceiving. King scored a 58 percent positive approval rating in mid-October, but only received 53 percent in the election. Because the senator is an Independent and the Democrats with whom he caucuses did file their own candidate, the next closest opponent scored 35 percent. Therefore, his political standing still proved strong.
On the other end of the spectrum, the senator who improved the most from an upside-down favorability index rating to the vote was New Jersey Sen. Bob Menendez (D). While his October index was a poor 31:46 percent favorable to unfavorable, the worst by far among the 32 senators standing for re-election, he was successfully re-elected, 54-43 percent, over retired pharmaceutical company CEO Bob Hugin (R).