NASHVILLE, Tenn. (AP) — Former Ambassador to Poland and longtime Tennessee Republican politician Victor Ashe sued state election officials on Wednesday over a law he claims is so vague that he could be prosecuted for voting in a Republican primary.

The 1972 state law requiring primary voters to be “bona fide” party members or “declare allegiance” to the party has rarely been invoked, but legislators voted this year to require polling places to post warning signs stating that it’s a crime to vote in a political party’s primary if you are not a bona fide member of that party.

Ashe and other plaintiffs challenge both laws in the lawsuit filed in federal court in Nashville. They argue that Tennessee voters aren’t registered by party, and the law does not define what it means to be a bona fide party member, to declare allegiance to a party or long that allegiance must last. Such vague terms invite arbitrary enforcement and are likely to intimidate otherwise legitimate voters, the suit claims.

“Vague statutes that chill the freedom to fully participate in the political process are unconstitutional,” the lawsuit states. The plaintiffs are asking a judge to declare the voting laws unconstitutional and prohibit their enforcement.

Ashe says in the lawsuit that although he is a lifelong Republican who has served as both a state senator and state representative as well as mayor of Knoxville, he also routinely and publicly criticizes his fellow Republicans in a weekly column for the Knoxville News-Sentinel.

“Ashe reasonably fears that the people in control of today’s Tennessee Republican Party may not consider him a bona fide member affiliated with the party and could seek to prosecute him if he votes in the next primary election,” the lawsuit states.

Another plaintiff is real estate developer Phil Lawson, who is a Democrat but has also voted for Republicans and made financial contributions to Republican candidates. The League of Women Voters of Tennessee is the third plaintiff. The civic organization that helps register voters says it doesn’t know how to accurately inform them about the primaries without subjecting them to potential prosecution. The league also worries that volunteers could be subject to a separate law that punishes people who promulgate erroneous voting information.

Tennessee voters often decide which primary to participate in based on campaign developments. The partisan balance in Tennessee means many local elections are decided in the primary, with the large cities leaning heavily Democratic and most other areas leaning heavily Republican. It is not uncommon for people to vote for one party in local elections and a different party in federal or statewide elections.

Republicans, who control the Tennessee legislature, have discussed closing primaries for years, but the idea is controversial and has never had enough support to pass.

The lawsuit names Tennessee Secretary of State Tre Hargett, Coordinator of Elections Mark Goins and Attorney General Jonathan Skrmetti as defendants. A spokesperson for Hargett and Goins directed questions to the attorney general’s office. A spokesperson for Skrmetti did not immediately respond to emails on Thursday morning.