WASHINGTON — Several weeks ago, the University of Illinois at Urbana-Champaign abruptly revoked a job offer to Steven G. Salaita in the wake of controversial Twitter posts by Mr. Salaita, a former professor of English at Virginia Tech, about Israel.

Now, two scholars have signaled their protest by pulling out of speaking engagements at the campus, while a program that was set to host a national gathering there has called its conference off. Meanwhile, the American Indian studies program, which Mr. Salaita had been set to join, is scrambling to make up for his absence.

Mr. Salaita had been offered a job as a tenured professor of American Indian studies, but his appointment was contingent upon approval by the university’s Board of Trustees. Earlier this month administrators told Mr. Salaita in a letter that they would not bring his appointment before the board after all. An affirmative vote, they said, was unlikely.

The decision, which raised questions about contractual loopholes and academic freedom, almost immediately drew pushback from the academic community. Thousands of scholars in a variety of disciplines signed petitions pledging to avoid the campus unless it reversed its decision to rescind the job offer. A number of prominent academic associations also urged the university to reconsider.