Professors, graduate assistants and clerical workers at Southern Illinois University Carbondale are threatening to strike next week to protest sluggish labor negotiations.

The move could disrupt classes for some 20,000 students, though administrators are promising to keep the campus running, using substitutes where needed.

"We think we can fill the classrooms with qualified instructors in almost every case," said Rod Sievers, a university spokesman.

At the heart of the unrest are four bargaining units of the Illinois Education Association, which have been working without contracts — and under conditions imposed by the university — for more than a year. Representatives said they're frustrated by a lack of progress, with some accusing the university of trying to destroy collective bargaining on campus.

Anita Stoner, an assistant professor of journalism and president of the Non-Tenure Track Faculty Association, characterized negotiations as "glacial" as she prepared to leave her office for a bargaining session earlier this week. Little has changed, she said, since the unions set the deadline.

"We're going on strike next Friday, and we've met once in the last two weeks," said Stoner, whose unit is looking for better job security and more clarity in how layoffs are decided.

In the end, she said, the unions may have no choice but to strike: "What else can we do? We've tried every other diplomatic option."

The university, however, downplayed talk that it is refusing to negotiate and said officials are working to find compromises with the unions.

"To say we're not bargaining in good faith is simply wrong," Sievers said. "We've been talking with these guys a lot."

If they do strike, it's unclear just how effective they'll be. The school, like others around the nation, faces financial difficulties at a time when states are cutting back on higher education funding. And unlike many schools in the region, SIUC has not seen significant increases in enrollment and tuition dollars.

While campus strikes aren't seen all that frequently, several strikes or threats of strikes have taken place recently at schools around the nation, including Rider University in New Jersey, Cincinnati State Technical and Community College and Central Michigan University.

There's also talk of one at Lewis and Clark Community College, where faculty recently rejected an offer by the school after more than five months of talks. No deadline has been set, but faculty negotiators say that could change before the start of next semester.

"If an agreement is not reached soon, the spring semester could be impacted," said Michael McDermott, the UniServ Director for the Illinois Education Association who is assisting the union.

Yet even when a work stoppage happens, it doesn't tend to last long, said Richard Boris, director of the National Center for the Study of Collective Bargaining in Higher Education and the Professions at Hunter College in New York.

"Faculty strikes are mostly symbolic and very short-lived and exist to jump-start conversations that have stalled," Boris said. "The brake on every faculty strike is the harm that lost classes will bring to students."

And while SIUC is hopeful classes won't be canceled, Boris said schools often have trouble keeping things running — with no ready source of replacement instructors.

It would, of course, seem to depend on how much support the strike enjoys. Some 3,400 employees, representing a wide range of salaries, are eligible to be members of the four bargaining units, though most do not join.

So the school may be aided by faculty who refuse to take part. Sievers said some retired faculty members also have offered to fill in.

"It's a university town. There are a lot of folks here," Sievers said.

Negotiations are complicated by the fact that SIUC is bargaining with four distinct units — representing tenure track faculty, nontenure track faculty, graduate assistants and civil service workers — each with different concerns.

The Association of Civil Service Employees, whose workers include clerical employees and lab techs, wants to be free of unpaid furloughs and assurances that they won't be replaced by students and temporary workers. Since early 2010, the unit has lost nearly 20 percent of its eligible workforce.

Bargaining chairwoman Tammy Keen said the school has offered nothing.

"We have asked for things that we could live without," Keen said. "But there has just been no bargaining at our bargaining table. There has been no give and take."

The Faculty Association, which represents tenure track instructors, wants more accountability from the school when it makes decisions on layoffs and other cuts. Members want more specific criteria on what constitutes a financial exigency, or crisis, that allows the school to cut tenured positions. And they want more control over which classes are taught online, along with safeguards against certain pay cuts.

"A contract that doesn't protect your salary is a pretty meaningless contract," said Dave Johnson, an associate professor of foreign languages and spokesman for the Faculty Association.