[Updated (1/29/2015, 2:52 p.m.) with the university’s response.]

Steven G. Salaita’s widely anticipated lawsuit over the University of Illinois’s decision to deny him a tenured professorship takes the innovative step of also demanding damages from university donors who pressured its leaders not to hire him.

Along with its expected targets—top campus and university-system administrators, and nearly all of the system’s trustees—Mr. Salaita’s federal lawsuit names as defendants several as-yet-unidentified donors who threatened to withhold money from the university if it made good on its job offer to him.

The donors, and many others, had opposed the university’s plans to hire Mr. Salaita as a professor on its Urbana-Champaign campus because they objected to his inflammatory criticisms of Israel and argued that his statements were anti-Semitic. His lawsuit is in response to the university’s September decision to rescind its job offer to him.

In seeking compensatory and punitive damages from the donors, the lawsuit, filed on Thursday in the U.S. District Court for the Northern District of Illinois, says: “They each communicated with university officials regarding Steven Salaita’s employment and demanded that the university breach its contractual obligations and promises to Professor Salaita or else they would withhold financial contributions to the university.”

Whether the donors actually influenced the university’s decision to rescind its job offer to Mr. Salaita remains the subject of debate. Based on a review of his case, a faculty committee concluded in a report issued in December that it had found no evidence the donors influenced the decision of Phyllis M. Wise, chancellor of the Urbana-Champaign campus, to have the scholar’s job offer withdrawn.

Mr. Salaita’s lawyers argue otherwise, however, and one of his lawsuit’s claims against Chancellor Wise accuses her of violating the state’s open-records law by destroying a potential smoking gun, a two-page memorandum from a donor arguing against the scholar’s appointment.

The lawsuit identifies the sued donors only as “John Doe” defendants because the university redacted their names from copies of email exchanges with them released to the news media and other third parties under the state’s open-records law. If the court upholds the donors’ status as defendants, the university presumably can be subpoenaed to provide their identities.

The lawsuit accuses the donors of wrongful interference with contractual and business relations, and includes them in its claims that all of the defendants conspired to violate Mr. Salaita’s First Amendment free-speech rights and intentionally inflicted emotional distress upon him.

The university said in a written statement that Mr. Salaita had demonstrated that he “lacked the professional fitness” to serve on its faculty.

The statement cited a series of Mr. Salaita’s tweets and said the messages showed that he did not have the “judgment, temperament, and thoughtfulness to serve as a member of our faculty in any capacity, but particularly to teach courses related to the Middle East.”

The university vowed to defend itself and called Mr. Salaita’s claims meritless.

At a news conference held in Chicago on Thursday, Anand Swaminathan, one of Mr. Salaita’s lawyers, stressed that the lawsuit was not directed at donors who merely had told university officials about objections to his hiring, but at donors who had threatened to withhold money if he received a position there. “People should not be able to use their financial wealth to inject themselves into a university’s hiring process,” he said.

Maria LaHood, a senior attorney with the Center for Constitutional Rights, which is helping represent Mr. Salaita, said the donors listed as defendants so far included a smaller number of “high profile, wealthy donors who had direct contact with Chancellor Wise.” She added, however, that other donors might be included as defendants if other evidence of donor interference in the university’s decision was uncovered through the lawsuit’s discovery process.

The lawsuit lists as defendants—along with the donors; Chancellor Wise; Robert Easter, the university’s president; and Christophe Pierre, its vice president—every member of the university’s Board of Trustees except James Montgomery, the lone board member who voted against the decision not to hire Mr. Salaita.

Among its claims that do not involve donors, the lawsuit accuses the defendant administrators and trustees of violating Mr. Salaita’s First Amendment speech rights and due-process rights, and says the defendant trustees violated a contract and a promise of employment in denying him a job he had already been offered.

“Through its actions, the university administration not only violated Professor Salaita’s constitutional right to free speech, they also trampled on long-cherished principles of academic freedom and shared faculty-administration governance of the university,” the lawsuit says.

Mr. Salaita had quit his previous position, a tenured professorship at Virginia Tech, in the expectation of assuming his Illinois job at about the time it was rescinded. In describing the harm done to Mr. Salaita by the episode, the lawsuit says, he has been “denied the opportunity to teach, is jobless and without tenure, and his academic career is in shambles.”

“Moreover,” the lawsuit says, “without a university affiliation, Professor Salaita suffers irreparable harm since, among other things, his ability to publish articles in academic journals and to present his scholarship to his colleagues is severely diminished.”

Mr. Salaita has filed a separate lawsuit in state court seeking access, under Illinois’s open-records law, to administrators’ email correspondence with donors and other documents. The court is scheduled to hold a February 13th hearing on a university motion to dismiss that case.