George Bush delivered a State of the World address to Congress Tuesday night offering a vision of an American future at home that depends on the role that America is able and willing to play abroad.

Even for a foreign policy president, this is a remarkable admission. For a Republican president, it borders on political heresy. In its sweep and content, Bush's speech captured a generation of change and put the seal on the transformation of the Republican Party into the party of internationalism in American politics.

The once isolationist party of Robert Taft has become both presidential and internationalist in the past generation. The two changes are intimately related. Today the Democratic Party's leadership is as isolated from executive power and from a world role as the GOP was in the 1930s and 1940s under Franklin D. Roosevelt and Harry S Truman.

With American troops fighting in the Persian Gulf, Bush had to center his second State of the Union address on his foreign policy accomplishments. The fact that he possesses no domestic accomplishments also contributed to this approach.

But the way in which Bush described America's role in the world -- or, when decoded, the world's role in America -- underlined a reversal of political and national priorities that even the president still grapples to identify and explain.

Bush's declaration that the United States must continue to bear "the burden of leadership" in world affairs and make the 100 years ahead "the next American century" invites comparison not to Ronald Reagan or even to Richard Nixon, but to John F. Kennedy's call to Americans in his Inaugural address 30 years ago this month to "pay any price, bear any burden, meet any hardship" in the cause of liberty.

In the wake of Vietnam, these are sentiments few Democratic politicians would feel comfortable voicing today. Jimmy Carter's inept handling of Iran, of the Soviet Union and of the American economy have reinforced his party's insistence that foreign involvement must now be subordinated to a vast range of more urgent domestic interests.

Without directly joining the issue on Tuesday, Bush sketched an alternative vision in which American society profits morally and economically from leading the founding of the new world order Bush sees supplanting the Cold War. A sharp turn inward would harm American interests, he suggested.

Twice Tuesday night Bush underscored that increasing American exports to the rest of the world was the key to ending the recession quickly. He identified export growth, along with single-digit inflation and low inventories of manufactured goods, as one of the only three reasons for optimism about the American economy he could cite. Trade with Japan, the European Community and the rest of the world is the key "to more real jobs and more real growth" at home and abroad.

"We are Americans," Bush declared. We bear "a unique responsibility to do the hard work of freedom." Throughout he emphasized burden bearing instead of burden sharing, a major topic for Sen. George Mitchell in the Democratic response to Bush.

Mitchell of course was playing defense against a wartime president. Even so, his response seemed remarkably subdued. The America that emerged from his words is one that is tired, in debt, more eager to lay down its external burdens than at any time in the past half century. He presented the declinist view that Bush had preemptively dismissed as "looking the wrong way."

Many Democrats believe today that their party was gravely wounded by the hubris contained in Kennedy's Inaugural Address and Lyndon Johnson's interpretation of it. That helps explain why Bush's America resembled Kennedy's vision far more than did the America described by Mitchell.

But the Democratic renunciation carries a cautionary meaning for Bush. He does well to recognize, as I believe he does, that while his rhetoric can be Kennedyesque during the war, he will have to guide America into a far less expansive role when the war ends.

Bush faces an entirely different context than did the young Democrat. Kennedy embodied the confidence and vigor of a generation just coming to power at a time of decolonization and ideological conflict in the Third World.

Bush in fact belongs to that same generation. He and Kennedy were veterans of combat in the Pacific. Bush's presidency, likely to be the last of a World War II veteran, effectively ends that generation's hold on power.

He will bequeath a changed world rather than embody it, as Kennedy hoped to do. The peace that Bush will identify America with in that world must be a more important part of his legacy than the war he is waging today.