President Barack Obama is asking the world to confront the root causes of rage exploding across Islam, calling it a defining choice "between the forces that would drive us apart and the hopes we hold in common".
Mr Obama is to tell the United Nations General Assembly that the United States will not shrink from its role in troubled, transitioning nations despite the killing of four Americans in Libya, including US ambassador Chris Stevens. More than 50 people have died in violence linked at least in part to the anti-Muslim film made in the US.
Mr Obama will also to seek to show US resolve in preventing Iran from developing a nuclear weapon, an issue that has undermined White House relations with Israel's leadership. In his final international address before the November election, Mr Obama will stand up for democratic values on a stage afforded to presidents, not presidential challengers. He will use it to try to boost his political standing without mentioning Republican opponent Mitt Romney.
"Today, we must affirm that our future will be determined by people like Chris Stevens, and not by his killers," Mr Obama says in his speech. "Today, we must declare that this violence and intolerance has no place among our United Nations."
Mr Obama's comments will be scrutinised around the globe and by the gathering of presidents and prime ministers in the United Nations hall, given the tumult, terrorism, nuclear threats and poverty that bind so many nations. His emphasis will be on the unrest in the Muslim world and on Iran, whose disputed nuclear ambitions have unnerved much of the world and caused tension between the United States and long-standing ally Israel over whether Mr Obama has forcefully defined his breaking point for military action.
"Make no mistake: a nuclear-armed Iran is not a challenge that can be contained," Mr Obama says. He adds: "That is why a coalition of countries is holding the Iranian government accountable. And that is why the United States will do what we must to prevent Iran from obtaining a nuclear weapon."
That language remains as specific as Mr Obama will publicly describe his "red line" for military intervention. Mr Obama's activities at the United Nations say plenty, too: There are not many of them. Campaigning is his imperative.
The dominant theme of the speech will be his response to the protests raging in places across the Middle East and North Africa. As he has for days, Mr Obama will condemn the violence, defend democratic principles of free speech and promise no US withdrawal of outreach.
Much of the growing anger is aimed at the United States because of the anti-Islam film produced in there, but the White House has now deemed the attack on its consulate in Libya a "terrorist attack" and has not ruled out the possibility it was premeditated. Mr Obama now says it "wasn't just a mob action."
"There are no words that excuse the killing of innocents," Mr Obama says in the speech. "There is no video that justifies an attack on an embassy. There is no slander that provides an excuse for people to burn a restaurant in Lebanon, or destroy a school in Tunis, or cause death and destruction in Pakistan."