UPDATE: Presidential polls still open in Iran, violence reported

Iran is keeping its polls open six hours longer than planned, to accommodate a massive turnout in its presidential election.

A reformer who favors better ties with the United States is the main challenger to hardline President Mahmoud Ahmadinejad.

A campaign organizer for the main election challenger to Ahmadinejad says about a dozen of the president’s supporters attacked one of the opponent’s campaign offices in Tehran with tear gas.

No one was injured. But it was the first report of violence in the presidential election.

President Barack Obama says Iran’s “robust debate” leading up to elections shows change is possible there, and it could boost U.S. efforts to engage Tehran’s leadership.

Obama said he has been excited to see the debate over candidates and celebrated that “you’re seeing people looking at new possibilities.“