BISMARCK, N.D. — Supporters of the University of North Dakota's Fighting Sioux nickname said Monday they believe they have enough signatures to force a statewide referendum on whether the school should keep it.

Backers of the nickname, which the NCAA considers demeaning to American Indians, planned to turn in petitions to Secretary of State Al Jaeger's office Tuesday night to demand a vote on whether the Grand Forks school should be required to use it.

The nickname's advocates need signatures from at least 13,452 eligible North Dakota voters to put the question on the June 12 primary election ballot. The vote would be about whether to restore a state law that says the University of North Dakota's athletics teams "shall be known as the ... Fighting Sioux."

The Legislature repealed the law last November.

The NCAA has said it would sanction UND for using the nickname by barring the school from hosting postseason tournaments and its athletes from wearing uniforms with the nickname or logo during postseason play.

Sean Johnson, a member of the referendum's sponsoring committee, said signature-gathering efforts would continue until shortly before the midnight Tuesday deadline for turning in petitions.

One signing location Tuesday night will be in front of the state Capitol itself, a few hundred yards from Jaeger's office on the Capitol's ground floor.

Johnson said Monday he believed the nickname's backers had the minimum number of signatures they need to qualify for a vote.

However, having extra names is important in case some signatures are disqualified, as often happens when the secretary of state reviews the petitions, he said.

"The University of North Dakota belongs to North Dakotans, and they should have a say in what the team is called," Johnson said.

Since the Legislature repealed the law in November, UND already has taken steps to retire the logo and nickname.

The American Indian profile logo has been removed from university websites, and the school has asked news outlets to avoid using the Fighting Sioux nickname.

Peter Johnson, a university spokesman, declined comment on the issue Monday.

If the petitions are turned in Tuesday and appear to have the required minimum number of names, the pro-nickname law that the Legislature agreed to repeal in November will be allowed to stand.

Jaeger has 35 days to review the petitions and undertake a random sampling of names to see if they are valid. He will then decide whether to certify the petition for a June vote. Should the petition fall short of its signature goal, the repeal of the pro-nickname law will again take effect.

Nickname supporters are also circulating a separate petition that advocates a pro-nickname amendment to the North Dakota Constitution. It would add this sentence: "The University of North Dakota and its intercollegiate athletic teams shall be known as the Fighting Sioux."

The constitutional amendment initiative requires at least 26,904 petition signatures. The petition must be turned in to Jaeger's office by midnight Aug. 8 to qualify for the November general election ballot.