(CNN) -- An agreement could be reached before week's end between Washington University students and an Illinois nightclub that allegedly barred six African-American students while admitting nearly 200 of their white classmates.

Fernando Cutz, senior class president at the university in Missouri, said the aggrieved students have been in contact with lawyers representing Original Mother's, a bar in Chicago's Gold Coast neighborhood.

The two sides expect a resolution to their dispute as early as Wednesday, Cutz said. He did not, however, say what the students were demanding or why he was optimistic that a deal could be struck.

The students complained to state and federal agencies after six African-American members from their senior class trip celebration were denied admission to the club on October 17.

Bar personnel cited dress code violations -- specifically baggy jeans -- in barring the African-American students, Cutz said.

A white student and a black student then exchanged jeans to see what would happen. The white student was admitted, while his classmate still was kept outside, Cutz said.

Calls from CNN to the nightclub were not immediately returned. The bar told the Chicago Tribune newspaper that it was investigating.

The celebration at Original Mother's was to top off a two-day senior class trip to Chicago, Cutz said. The party had been arranged with the bar in advance by the student class board, which includes two of the African-American students who were later denied entry, Cutz said.

He said he was already inside the bar with some 200 other students, none of whom are African-American, when the first group of African-American classmates arrived. Cutz said he quickly learned that the manager of the bar had denied the six students entry, and he said the manager told the students their baggy pants violated the bar's dress code.

Cutz, who is white, said he confronted the manager. "These six [students] were better dressed than I was," Cutz told CNN.

He told the students to "go back to the hotel and change." But the manager of the bar stepped in to say that he had made his decision and that the six men could not return to the bar even if they changed clothes, Cutz said.

The students became "more agitated" and "set up an experiment," Cutz said.

Class Treasurer Regis Murayi, who is black, exchanged jeans with a white student, Jordan Roberts, who -- being 3 inches shorter than Murayi -- looked "substantially baggy."

Roberts approached the same manager who had turned away the African-American students, paid the entry fee and was allowed in, Cutz said.

CNN's Susan Candiotti also contributed to this report.