Former Republican presidential and senatorial candidate Alan Keyes was arrested Friday at a protest of President Obama's impending commencement address on the campus of Notre Dame University.

Keyes, Obama's 2004 opponent in the Illinois Senate race, was arrested for trespassing along with 25 other protesters at Notre Dame, Chicago Breaking News reported.

Keyes, a conservative Catholic, was protesting the president's upcoming speech. Some Catholics have called on Notre Dame, a premier Catholic university, to rescind Obama's invitation due to his support for abortion rights, which the Catholic church opposes.