"Stop the bigotry!" the demonstrator shouted as he hurled the liquid Thursday night during the program at Western Michigan University. The incident came just two days after another noted conservative, William Kristol, was struck by a pie during an appearance at a college in Indiana.
After he was hit, Buchanan cut short his question-and-answer session with the audience, saying, "Thank you all for coming, but I'm going to have to get my hair washed."
The demonstrator, identified by authorities as a 24-year-old student at Kalamazoo Valley Community College, was arrested and faces a misdemeanor charge of disturbing the peace. He was released on a $100 cash bond, pending his April 14 arraignment.
"He could have faced a felony assault charge, but Pat Buchanan decided to not press that charge," university spokesman Matt Kurz said.
Buchanan's visit had evoked controversy on campus because it fell on the birthday of the late Mexican-American labor leader Cesar Chavez. Buchanan favors tighter controls on immigration.
Kristol, editor of the influential conservative magazine The Weekly Standard and former chief of staff to Vice President Quayle, was splattered by a student during a speech Tuesday at Earlham College in Richmond, Ind.
Members of the audience at the Quaker college jeered the student, then applauded as Kristol wiped the pie from his face and said, "Just let me finish this point." Kristol then completed his speech and took questions from the audience.
The student, who was not immediately identified, was suspended and could face expulsion following a disciplinary review, Earlham Provost Len Clark said Wednesday.
Clark also issued a written apology complimenting Kristol for his "graciousness."