There was little coattail effect on candidates Dan Cox endorsed in the Primary
On July 19 Dan Cox succeeded in the Maryland Republican gubernatorial primary. Much digital ink has been and will continue to be spilled on that result. Most is focused on what Cox’s win means for the future of Larry Hogan, the Maryland Republican Party, and various other candidates throughout the state. However I want to take a moment and examine another question:
Did Dan Cox actually have any coattails?
It’s all well and good to win an election. But there is a substantial difference between just winning yourself and winning while bringing in a strong core of support that is part of your camp. This is particularly true for a divisive, insurgent candidate like Cox, especially given the paucity of endorsements he received from his colleagues in the General Assembly - 3 total, 1 of which came from former delegate Warren Miller (interestingly of the sitting delegates who endorsed him, Dan did not give an endorsement back to Joe Boteler). Should Cox prevail in the primary a lack of candidates swept in with him will make implementing his agenda, already a herculean task for any Republican governor, even more challenging.
Coattail effects are also a useful tool for disentangling how much voters were voting for a given candidate versus voting against whatever that candidate opposed. This is another area where insight would be helpful given how heavily Cox’s campaign was probably more anti-Larry Hogan than it was pro-Dan Cox. Or put it another way - did voters trust and agree enough with Cox to listen to him about other candidates or were they just voting to show their unhappiness with the current governor?
So we know why coattails matter, but were there any? Let’s take a look at the data.
From the list of endorsements on his site, Cox made the following endorsements:
1 for Attorney General
2 for US Congress
5 for State Senate
10 for House of Delegates
7 for County Offices
4 for Central Committee
Of those Cox’s endorsees did as follows:
1/1 for Attorney General
0/2 for US Congress
2*/5 for State Senate (both victories were uncontested races)
4*/10 for House of Delegates (2 of the 4 races were uncontested and a 3rd was incumbent Ric Metzgar seeking re-election)
3/7 for County Offices
1/4 for Central Committee
For those keeping score at home, that is, at best, a 38% success rate. Realistically it’s more like 29% since uncontested races can’t have any coattail effect (arguments run both ways as to whether Del. Metzgar should count since it was contested but he’s an incumbent).
Based on those raw numbers, it seems clear that any coattail effect for Cox was minimal. We can also break things down further by looking at the difference between Cox’s performance and that of his endorsed candidates in each of those districts. That data doesn’t appear to be readily available in most races but it is available for statewide and countywide races at least.
That’s an average of Cox endorsed candidates running 15.75 points behind Dan and a median of 9.5 points behind. That is a pretty meaningful number of people who were willing to vote for Dan Cox but not for candidates that Cox actively endorsed.
It is somewhat less illuminating but we can also look at the difference between Cox endorsed candidates and the victors (where Cox endorsees lost) and losers (where his endorsees won). Looking at that, Cox candidates on average lost by 13 points. Among the losing endorsees, losses averaged at 20-point losses while among the few winners the average was only an 8-point margin.
Correlation may not be causation, and we are admittedly missing a lot of data (in particular how Cox ran vs his endorsed candidates on a district-by-district basis), but I think the data paints a pretty clear picture - Cox had effectively no coattails to speak of. The severe disconnect between Cox’s own results and those of his endorsees and how badly so many of his endorsees lost also speaks to the likelihood that Republican primary voters were not necessarily enthused about Dan Cox but wanted to punish Larry Hogan and his perceived successor for dissatisfaction with his time as governor.