THOUGH HE FIRST won worldwide attention as a superb Olympic sprinter, it was the courage of his political convictions four decades later that earned new and lasting respect for Ralph H. Metcalfe, the Democratic congressman from Chicago who died Tuesday at the age of 68. For all Americans, particularly black Americans, Mr. Metcalfe's performances in the Olympic Games of the 1930s were certainly proud moments in history - most notably at the tense 1936 games in Berlin, when he won a gold medal on the U.S. relay team and a silver medal for finishing second to a fellow black American, Jesse Owens, in the 100-meter dash.

In the 1950s, Mr. Metcalfe's career in politics got off to a fast start as well, when he first won election to the Cook County Democratic Committee and attracted the attention of the late Chicago mayor Richard J. Daley. As Mayor Daley's handpicked president pro tem of the Chicago City Council, Mr. Metcalfe went on to become one of the mayor's most trusted black lieutenants - a comfortable position, for Mayor Daley had the city's black vote in his pocket. So it was that Mr. Daley tapped Ralph Metcalfe to take over the U.S. House seat of the late Rep. William Dawson in 1970.

It was widely assumed at the time that Mr. Metcalfe would continue as a down-the-line Daley lieutenant in Congress. And in the beginning, even as a founding member of the Congressional Black Caucus, he did serve the machine faithfully. But the caucus experience - working with younger, black-activist members of Congress - contributed to a dramatic break with Mayor Daley over police brutality in Chicago.

"I know the political reality of what I am doing," said Mr. Metcalfe in 1972, "but I am prepared to let the chips fall where they may. I'm willing to pay whatever political consequences I have to, but frankly, I don't think there will be any . . . . In the caucus we have decided to put the interests of black people first - above all else, and that means even going against our party or our political leaders if black interests don't coincide with their positions."

Though Mayor Daley eventually stripped him of all patronage powers and promoted a machine-backed opponent, Ralph Metcalfe won reelection and new recognition as a leader in Congress. It is that leadership, maturity and compassion that will be remembered best by the Americans of all races whom Ralph Metcalfe courageously served in his final years.