A group that sought to halt a new weapons plant in south Kansas City has dropped its effort to get a petition initiative on the November ballot.

The Kansas City Peace Planters had gathered more than 4,300 valid petition signatures to place a measure on the November ballot. It sought to prevent the manufacture of non-nuclear components for nuclear weapons and to convert the plant into a facility for “green technology.”

But the city council voted 12-1 against putting the measure on the ballot, saying it was unconstitutional, since it violated federal powers to set defense policy and interfered with numerous contractual obligations.

The Peace Planters had gone to court in Jackson County to try to get a judge to force the city to place the measure on the ballot. The two sides were expected to square off in court this morning. But the Peace Planters just put out a press release saying they are dropping their court fight.

“Our differences of opinion about the issue of nuclear weapons are great, but in a rare display of civility in our seemingly ever-too-contentious society, we were able to dialogue candidly with the parties and share important information,” petition coordinator Rachel MacNair said in the release.

The group said that, based on the review of documents, they had concluded that even if they prevailed in court this week, all parties would be embroiled in litigation for a prolonged period.

MacNair said by phone this morning that the group became convinced that, even if they prevailed with voters in November, the city council would have just repealed the measure at the first opportunity.

“We don’t go under the rules of power politics,” MacNair said, adding that the group is a “social movement.”

She said the group accomplished its mission of raising awareness and educating the public about the plant, and will continue its peace efforts in new ways, with more details to come.

Councilman John Sharp, who represents the south Kansas City District where the plant is under construction, said the city had always been confident it would keep the measure off the ballot. He said the economic consequences of halting the project would have been devastating.

“We knew we were on solid constitutional ground,” he said. “To stop the biggest construction project in the metro area in mid-stream would’ve been a terrible blow to our economy.”