Gov. Jay Nixon is calling the Missouri General Assembly into a special session next week to consider incentives for a major aircraft manufacturing plant, but local legislators said Friday the details aren’t yet clear.

The Boeing plant would be in St. Louis, potentially creating thousands of jobs, benefiting that area and expanding the state’s tax base. Boeing is looking at where to build its 777X, a commercial jet, and it’s set a Dec. 10 deadline for states to make their best offers. Missouri, which has major Boeing operations and thousands of jobs in St. Louis, is among several states trying to get the plant. The company says it’s sent out requests for proposals to about a dozen locations.

“It’s potentially a very big deal. It really is. So it’s worth looking at,” said Rep. Mike Cierpiot, R-Lee’s Summit.

Cierpiot, the assistant floor leader in the House, said the governor is scheduled to speak to House Republicans early Monday afternoon. The special session officially starts late in the afternoon, and legislators said it seems likely they’ll be in Jefferson City for a few days to decide the issue.

Nixon met with Boeing executives last week in St. Louis and later issued a statement in which he said the meeting had been “extremely productive.” The incentives he wants legislators to approve would be up to $150 million annually.

Boeing initially offered to build the 777X in Washington state but sought concessions from union machinists. After the union rejected a proposed contract, Boeing started talks with other locations. Washington state still plans to compete.

“Certainly we want to promote economic development,” said Rep. Jeanne Lauer, R-Blue Springs, who serves on the House committees on economic development and small business. But she said she’ll need to see the governor’s plan in detail.

Rep. Noel Torpey, R-Independence, is chairman of the House Small Business Committee. He’s also on the Economic Development and Fiscal Review committees, two committees through which Nixon’s plan would have to pass. He said he supports the basic idea of the Boeing plan and suggested the incentives could be directly tied to the number of jobs created.

“We’ll see,” he said Friday. “Everyone needs to vet the bill thoroughly. Nobody wants to pass a bill that’s detrimental to the state.”

Cierpiot said if the state is handing Boeing money, that’s problematic given the state’s tight budget. If Boeing is instead bringing growth to the state and wants some of that rebated, that’s a different equation, he said.

The Boeing question is to be the focus of the special session, though other large and costly issues will remain for legislators when they gather in January for their regular 2014 session. Lauer said the Boeing question is just part of what she likens to a Rubik’s Cube: Nixon wants a shot at the Boeing plant. He also wants to expand Medicaid and to fully fund primary and secondary education. Legislators want tax cuts, and some want tax-credit reform.

“So the question is going to be, where is the meeting of the minds?” she said.

As for where her fellow legislators stand, “I think it is totally mixed,” she said.

Nixon’s office says the aid for “large scale aerospace projects” would be offered through four existing Missouri programs that help finance job training and infrastructure improvements and reward companies for expanding their payrolls.

“Building this next-generation commercial aircraft in Missouri would create thousands of jobs across our state and secure our position as a hub for advanced aerospace manufacturing – and that’s why I am committed to competing for and winning this project,” Nixon said Friday in an emailed statement.

Legislative leaders have generally supported the Boeing project but have reserved judgment on the specific incentives package.

“I think it’s exciting that we’re being considered, but we are a long way from being awarded the contract,” said Speaker of the House Tim Jones, R-Eureka. “We just have to put our best foot forward.”

Missouri lawmakers in recent years have signed off on large state incentives packages aimed at specific industries.

Lawmakers in 2008 authorized $240 million of tax credits for Bombardier Aerospace to build passenger jets near Kansas City International Airport, but the company chose to manufacture them near its Montreal headquarters.

Two years later during a special session, Missouri authorized up to $150 million of incentives over a decade for the automotive industry. Ford and General Motors have used those to expand production in the Kansas City and St. Louis areas.

The Associated Press contributed to this report.