In the US they have a system of primary elections in which voters chose a candidate for each party, who then go to the main election. This has been criticised for increasing the polarization of US politics.

Is it possible for a US citizen to legally vote in both the Republican and Democratic primaries? If so, then would a movement to encourage this to help to reduce polarization by enabling a candidate to win nomination with more centrist policies?


State law determines the rules of primaries and not all states have primaries. I am not aware of a single state that would allow you to participate in both Republican and Democratic primaries or caucuses during the same election.

Some states have open primaries where you don't have to affiliate yourself beforehand and get to choose which one to participate in, but you can't participate in the other without risking being charged with a crime. Generally if there's a runoff in one of the primaries you can only participate in the runoff for the one that you participated in.

Others have a semi-closed primary (or semi-open if you prefer), where only unaffiliated (independents) get to choose, registered Republicans and Democrats can only participate in their respective primaries.

Still other states don't have a primary system at all but a caucus system in order to choose their party nominees, and those rules vary from state to state. Iowa is the first caucus in the election season so it winds up getting the most attention nationally, but other states that caucus in some form are Alaska, Colorado, Hawaii, Kansas, Louisiana, Maine, Minnesota, Nebraska, Nevada, North Dakota, Washington, and Wyoming. The Texas Democratic Party had a complicated system that included both a primary and a caucus, but the national party got rid of it in 2015. In 2008, even though Hillary Clinton won the popular vote, Barack Obama won the caucus and received more delegates from Texas in total than Clinton.

If so, then would a movement to encourage this help to reduce polarization by enabling a candidate to win nomination with more centrist policies?

Maybe, but with primary turnout in 2016 at around 29%, I would think it just as likely partisans from both sides would attempt the opposite by voting for the more extreme candidate in the opposing primary hoping it would make it easier for their preferred candidate to get elected in the general election. We can't predict the future impact or how people will choose to vote.

And while the merits of each system can be debated, ultimately the government can't force the parties to choose who will represent them in a particular way, it's the parties who have to choose. Viable "third parties" could upset the current status quo, but since the two main parties have such high incumbency and structural advantages you often see those candidates who might not actually be party members aligning themselves with one of the two in order to gain their support and avoid becoming nothing more than a spoiler. In my mind further polarization makes the likeliness of third party genesis higher as those left in the middle feel left behind, but the two major parties have been pretty adept at staying in power for quite a long time.

  • adding on: I was shocked to learn that under OHIO law changing one's registration (for party afflliation) - which is completely legal, can be considered election registration fraud if the registrant does not embrace the principles of the party to which they are registered. Thus changing your registration to enable the voter to primary vote for a specific candidate, while not embracing the principles of that party is illegal. Thus the idea that the peculiarities of each state makes analysis of national voting "rules"very complex is quite an understatement
    – BobE
    Oct 28 '18 at 15:28
  • @BobE, do you have any reference for that? I can't see any information about "embracing principles" wrt party affiliation at the Ohio Sec'y of State's site, either on the FAQ or a recent press release on 2018 affiliation changes. Oct 28 '18 at 18:21
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    @user4556274 See Ohio Revised code 3513.19 Para B that refers to a voter being challenged for a primary election: "When the right of a person to vote is challenged upon the ground set forth in division (A)(3) of this section, membership in or political affiliation with a political party shall be determined by the person's statement, made under penalty of election falsification, that the person desires to be affiliated with and supports the principles of the political party whose primary ballot the person desires to vote." (emphasis added)
    – BobE
    Oct 28 '18 at 21:24
  • @BobE Interesting. However I haven't been able to find any single short set of principles for either party. They have detailed platforms of course, but merely disagreeing with part of a platform shouldn't mean you can't vote in a primary. So how would eligibility under this clause be determined? Oct 29 '18 at 8:32
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    @user4556274 and Paul Johnson -follow up on Ohio Law issue: Local BoE says that the Ohio Supreme Court decided a case brought on this matter several years ago - that case law has effectively nullified the statute, however the legislature has never seen fit to change the statute accordingly.
    – BobE
    Oct 31 '18 at 2:36

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