The United Auto Workers has called a national strike against General Motors, following tense negotiations between the company and union leadership.

The strike will take effect midnight Sunday. The strike was announced Sunday morning after a meeting with union leaders.

The union said it is asking for fair wages, affordable health care, shared profits, job security and a defined path for seniority for temporary workers.

“We stood up for General Motors when they needed us most. Now we are standing together in unity and solidarity for our Members, their families and the communities where we work and live,” said UAW Vice President Terry Dittes in an online statement.

The strike includes thousands of Hoosier auto workers who work at GM locations in Indiana.

GM strike:How UAW work stoppage affects Indiana

A GM vehicle assembly plant in Fort Wayne employs about 4,300 UAW-unionized workers, said union shop chair Rich LeTourneau. If the strike takes place at midnight as planned, it will be seriously affected, LeTourneau said.

"All the strikes that we’ve been through over the years were headcount issues, manpower issues," LeTourneau said. "This one here is more dollars and cents, health care benefits. It will impact our members greatly.”

More than 6,800 Hoosiers work at four GM locations. The Fort Wayne assembly plant is the largest, followed by the Marion Metal Center, which employs 979 auto workers.

Bedford Casting Operations employs 933 total workers, and another 420 work at a components holding facility in Kokomo.

How Indiana could be affected

The risks in a nationwide strike are high, said Eric Schansberg, a professor of economics at Indiana University Southeast who studies labor economics.

Schansberg said when unions engage in a strike, they take a calculated risk based on how much they think the other party can give. In this case, he said, it's not clear how much GM is willing to budge.

"Short term, I mean, it just moves the bargaining to a different level," Schansberg said. "And long term, it's just not clear because it comes back to, how much can GM really give? UAW is really taking a big chance when it comes to long term.”

Communities around Indiana's GM locations will be mildly affected by a short-term strike, said Michael Hicks, a Ball State University economist, and businesses are likely to feel the hit first.

UAW workers on strike are only paid $250 per week while striking, a much lower amount than many are accustomed to earning.

"Their incomes are going to drop significantly," Hicks said. "And because of that, they're just not going to have the resources probably, to spend. ... Think about it more like a snowstorm that causes people to cut back spending for a few days.”

If the strike goes on longer, Hicks said, it could have a larger economic impact.

"It could go to the level of the strikes that we saw in the 1970s and early '80s, which protracted for many months and prompted severe economic hardship across the country where the plants were located," Hicks said.

Increased competition has made strikes into riskier bargaining tools, Schansberg said. If GM refuses to comply with union demands, the company could decide to hire non-union workers or move jobs overseas.

If the strike goes as planned and UAW workers secure higher wages, Schansberg said, it wouldn't have a large impact on the state economy.

But if the strike progresses and things go south, Schansberg said, the impact could be much bigger. If GM decided to close Indiana locations because of the strike, it could hurt the state economy.

"From a macro perspective, there's not a lot of upside," Schansberg said. "It would be devastating to the state economy, to the towns, cities, regions (GM is) located."

Hicks said he's not so sure the strike will work in the union's favor.

"Had they struck 18 months ago, maybe they would have had a much more significant opportunity to be successful with this," Hicks said. "But with auto sales softening and manufacturing in decline, it's not at all clear to me that they're going to be successful."

Negotiations

The strike is the first nationwide strike since 2007, the Detroit Free Press reported. The union represents 46,000 GM workers, including thousands in Indiana.

The move follows multiple negotiations with GM, after the union announced Saturday it would not extend its GM contract, which expired at midnight that night.

In letters sent Saturday before the midnight deadline, Dittes told employees negotiations were still in place, and directed workers to show up for their shifts Sunday morning.

"We still have many outstanding issues remaining, including significant differences between the parties on wages, health care benefits, temporary employees, job security and profit sharing," Dittes said in a letter.

About 850 Aramark-employed maintenance workers also struck five GM locations in Michigan and Ohio at midnight Saturday.

The Free Press called it an "emotional scene" Sunday morning, as UAW automakers had to pass picketing maintenance workers represented by the same union on their way in for early shifts.

Hoosier perspectives

LeTourneau has had his position at the plant, which produces the GMC Sierra and Chevrolet Silverado, since 1997. He said he's seen many strikes in his time there, but this one is a little different.

"People are the biggest UAW and GM asset. And once they decide to put the people last instead of first, this is what happens," LeTourneau said. "If people start to become an afterthought and the business comes first, this is exactly what happens.”

About 800 UAW workers work out of the Marion Metal Center in Marion, Indiana, said the GM unit's shop chair Ryan Hiestand. The metal center provides GM assembly plants across North America with stamped metal parts, blanks and sheet metal assembly.

Hiestand said it's an emotional time for everybody involved.

"We’ve got faith in our top leadership and we have to trust the work that they’re putting in," Hiestand said. "I think everybody just wants to have a job and a place to go to work and provide for their family ... It's no different from what any other American wants."

Maintaining their reputation is just as important for the union as achieving their demands, Hicks said.

If the strike fails, or even if it succeeds but at the cost of workers going for an extended time without their full pay, it could cause some disillusionment with the organization.

"At the end of the strike, they have to convince members that this strike mattered. That their membership in this organization and the wages that they have paid to this organization somehow matter," Hicks said. "And I think that’s a much tougher sell.”

Contact IndyStar reporter London Gibson at 317-444-6043 or lbgibson@gannett.com. Follow her on Twitter @londongibson.