On May 1, a week before the end of the longest sit-in in Harvard history, Al Sharpton, one of New York's most prominent protest organizers, left Institute of Politics (IOP) planners in the lurch for the second straight week.

The controversial civil rights activist and president of the National Action Network called to cancel only one day before he was scheduled to give a speech at the ARCO Forum.

It was Sharpton's second cancellation in the past month.

Instead of giving a speech in the ARCO Forum on May 1, Sharpton and 12 other protesters were arrested for trespassing at a military base in Vieques, Puerto Rico, according to The New York Times.

Sharpton was initially scheduled to appear at the IOP a week earlier on April 24. He cancelled that appearance in order to attend protests in Cincinnati against the police shooting of an unarmed black teenager.

IOP officials yesterday expressed frustration at Sharpton's scheduling conflicts. Forum director Bill White said he doubts the Institute will seek Sharpton out as a guest in the near future.

"I don't think we're going to reach out and invite him again," White said. "If he reaches out and contacts us and convinces us he's not going to cancel again, we'd be happy to accommodate him."

Sharpton, who comes to speak at Harvard a few times each year, initially planned to come merely as a guest for a Kennedy School seminar in racial and ethnic minority leadership taught by Professor Kim Williams.

The IOP appearance, White said, was an added bonus.

"Sharpton was coming up anyway," White said. "And was interested in coming for the Forum also. He seemed enthused about it."

But in recent weeks, the longtime activist has become increasingly busy as candidates in the New York mayoral race compete for his endorsement, adding to his already hectic schedule.

Sharpton's spokesperson was unavailable for comment yesterday.

--Staff writer Christina S.N. Lewis can be reached at cslewis@fas.harvard.edu.