WASHINGTON (AP) -- White House adviser Karl Rove was confronted by more than a dozen protesters who blocked his car and threw things as he tried to leave a speaking engagement at American University, officials said.

Rove was attending a guests-only discussion of electoral politics Tuesday night sponsored by the American University College Republicans.

"It was their last meeting of the year, and Mr. Rove spent about an hour with the students," said Maralee Csellar, a university spokeswoman.

When Rove tried to leave a campus building, he was confronted by more than a dozen protesters who surrounded his car to prevent it from leaving, Csellar said.

"They were throwing unknown objects at the vehicle," said Secret Service spokeswoman Kimberly Bruce. She said members of the Secret Service asked the protesters to move. When they continued to block the vehicle's exit, campus police were contacted.

Campus police lifted some of the demonstrators from the asphalt and carried them out of the vehicle's path so Rove could leave the campus. There were no arrests or injuries, police said.

A telephone call seeking comment from the White House was not immediately returned.