DEBORAH AMOS, host:
President Obama's address tonight will be his first prime-time speech from the Oval Office and historically, presidents use the setting to send a message. NPR's national political correspondent Don Gonyea looks at some past speeches from the room.
DON GONYEA: The president sits at his desk. Framed family photos are visible in the background; there's an American flag right next to the window that looks out to the South Lawn. It's an image that barely changes, except what was once viewed in grainy black and white is now alive with color and in high definition. There have been defining moments.
President JOHN F. KENNEDY: This government, as promised, has maintained the closest surveillance of the Soviet military buildup on the island of Cuba.
President RONALD REAGAN: Today is a day for mourning and remembering. Nancy and I are pained to the core over the tragedy of the Shuttle Challenger.
President GEORGE W. BUSH: Today, our fellow citizens, our way of life, our very freedom came under attack in a series of deliberate and deadly terrorist acts.
GONYEA: Oval Office speeches have also included momentous announcements.
President RICHARD NIXON: Therefore, I shall resign the presidency, effective at noon tomorrow. Vice President Ford will be sworn in as president at that hour.
GONYEA: The power of the Oval Office speech really began with the rise of television. Presidential scholar Martha Joynt Kumar recalls that President Eisenhower used the setting when he sent federal troops to Little Rock to enforce court-ordered desegregation of schools.
Ms. MARTHA JOYNT KUMAR: He spoke at night and said: To make this talk, I have come to the president's office in the White House. I could've spoken from Rhode Island, where I have been staying recently, but I felt that in speaking from the House of Lincoln, of Jackson...
President DWIGHT EISENHOWER: ...of Jackson and of Wilson, my words would better convey both the sadness I feel and the action I was compelled today to make, and the firmness with which I intend to pursue this course...
Ms. JOYNT KUMAR: He meant business, and he wanted the public to know that.
GONYEA: And that is the exact, same message President Obama will try to convey tonight. As to why this president hasn't delivered an Oval Office address sooner, it's simply been a matter of choice. Certainly, there are other issues that might have warranted such a setting.
President BARACK OBAMA: And as commander-in-chief, I have determined that it is in our vital national interest to send an additional 30,000 U.S. troops to Afghanistan. After 18 months, our troops...
GONYEA: That speech, from December, was delivered in front of a military audience at West Point. And on issues relating to the economy, he's used other locations at the White House - the Grand Foyer or the Rose Garden.
Marlin Fitzwater, a press secretary to Presidents Reagan and George H.W. Bush, says those other White House settings tend to convey a president speaking for the entire U.S. government. But the Oval Office, he says, is more about the president and his direct relationship to the people - which brings us to the oil spill.
Mr. MARLIN FITZWATER (Press Secretary, Presidents Reagan and George H.W. Bush): As I understand it, he really wants to emphasize his own role - that he's doing it, that he understands it, that he's been down there, that he cares - and he's been having trouble getting that message across.
GONYEA: Fitzwater says there is one thing he remembers about every Oval Office address he witnessed from the inside: the anxiety in the final minute before the camera light goes on.
Don Gonyea, NPR News, Washington.