By Mark Listes

U.S. Senator Thad Cochran defeated challenger state senator Chris McDaniel by less than two percent in Mississippi’s Republican runoff primary on June 24.

McDaniel was defiant towards the unique election system that contributed to his defeat. He spoke about the partially open primary system in Mississippi that allowed Cochran to mobilize a voter base that is regularly absent from Republican primaries—Democrats. With Cochran winning by such a narrow margin, the question is, “Were these non-Republicans who didn’t vote in the original primary eligible to vote in the Republican runoff?”

The answer is yes.

Mississippi is among 39 states where primaries are not completely closed. So, when you live in Mississippi you can vote in whichever primary you like. In Mississippi, however, things are not that simple because if no candidate receives over 50 percent of the vote in the primary, the parties hold a runoff primary. In Mississippi, practice is that voters who participated in the first primary are barred from participating in other parties’ runoffs.This makes Mississippi one of only nine states that have partially open primaries.

Of the 50 states, only 11 have traditional closed primaries, and only 11 more have traditional open primaries. The other 28 states have primaries that are somewhere in the grey between open and closed.

An open primary is an election for a party nomination in which registered voters may cast a vote regardless of political affiliation. Democrats can vote in Republican primaries and vice-versa. Other parties’ voters and unaffiliated voters may also participate. Typically there are no subsequent consequences to casting these votes unlike in Mississippi.

A closed primary is the opposite. Only voters who are registered members of the party holding the primary may cast votes. So, the only people who are casting votes in the Republican primaries are registered Republicans. The same goes for other parties holding primaries.

So how did this play into the Cochran- McDaniel race in Mississippi? Cochran’s campaign targeted Democrats and Independents, portraying Cochran as a more compatible choice than McDaniel, who affiliated with the Tea Party.

 Enter Mississippi Democrats. They are a small portion of the electorate in Mississippi, but every vote counts in an election that is this close. Also, as long as they had not voted in the Democratic primary, they could vote in the Republican runoff. Pitching a message of a lesser of two evils, Cochran and his supporters spent more than $100,000 per day and targeted these voters. The tactic worked.

During the runoff, voter turnout increased in nearly every single county in Mississippi, and it had increased by even bigger gaps in counties that are predominantly Democratic, near 50 percent in some. Cochran, who had narrowly lost the first primary, won the runoff and the nomination.

As for the future of Mississippi primaries, “It’s too early to tell, but I expect we’ll see a lot of [closed primary] proposals,” said Senator David Blount, vice chairman of the Senate Elections Committee.  McDaniel, who is chairman of Mississippi’s Senate Elections committee, called the primary strange and unusual. Senator Blount also said that he would be opposed to these proposals because he believes “Mississippi voters ... want more choices and more accessibility, not less.”

For more information on how primaries are structured, see NCSL’s information here.

Mark Listes is a legal intern with NCSL’s elections program.