Vice President George Bush will present the U.S. case at Thursday's U.N. Security Council debate on the American destruction of an Iranian airliner, the White House announced Wednesday.

Bush said he "can't wait" to argue "the free world's case."White House spokesman Marlin Fitzwater made the announcement at his daily meeting with reporters and was repeatedly asked why Bush, the certain Republican presidential nominee, was being dispatched to the United Nations.

He answered that the appearance of Bush, a former U.S. ambassador to the United Nations, "reflects the importance of the issues at stake."

Fitzwater said Bush "will demonstrate to the Security Council and the world the U.S. concern on this matter, the seriousness with which we take it and our dedication to steps to try to end the Iran-Iraq war.

"That is our motivation."

Fitzwater denied that there was any political motivation behind Bush's assignment, telling reporters, "Let's deal with the real question here. The issue is that we believe that this is a matter of the highest importance to the United States and to the world."

Asked what role U.N. Ambassador Vernon Walters would play with Bush present, Fitzwater said "he will have the same role he would be expected to always have, which is to represent our views there, to participate in the discussion as appropriate."

The spokesman said he could not say how long Bush would remain at the United Nations, saying that "it's my understanding that his primary purpose is to present the American view tomorrow, but, beyond that, I don't know."