PIERRE (AP) – A group trying to bring a “top two” primary system to South Dakota didn’t collect enough valid signatures to get the issue onto the November ballot, the state’s chief elections official said Friday.

Secretary of State Shantel Krebs’ office said in a statement that a random sampling of signatures collected by Open Primaries South Dakota found that the campaign submitted about 25,500 valid signatures, not the nearly 28,000 needed for the proposed constitutional amendment to go to voters. The rejection could be challenged in court.

The group’s treasurer, De Knudson, said she’s contacted the group’s attorney but that a decision hasn’t been made on whether to challenge the decision.

“I’m just a little stunned right now,” said Knudson, a former Sioux Falls City Council member. “I’m just extremely disappointed.”

The amendment would have moved South Dakota to a system in which the top two finishers in a primary would have advanced to the general election, regardless of party. Such a model is sometimes referred to as a “jungle primary” system.

The proposal would have applied to primaries for county offices, the Legislature, governor and U.S. House and Senate. For example, in a gubernatorial race under the plan, there would be an open primary for all candidates in which the top two vote-getters would compete in the general election.

Supporters say the measure would be fairer because many elections now are effectively decided in partisan primaries closed to independent voters. In South Dakota, the Democratic primary is open to independents, while the Republican primary is closed. No groups had filed with the Secretary of State’s office to run a campaign against the proposal.

Knudson said the campaign used paid signature gatherers, and about 75 volunteers collected roughly 2,400 names. She said the group’s top volunteer circulator had already contacted her Friday to say he would gather signatures again to put the measure before voters.

Knudson said she thinks her group’s proposed system is much better than South Dakota’s current primary model.

“You don’t know what the future holds, but I believe that our group will be back even stronger in 2020,” she said.