WASHINGTON -- Out on the Democratic campaign trail you won't be hearing much about the gap between rich and poor in America. Nor about the way big corporations muscle their way around Washington. Nor about the threat that land mines still pose around the world. Nor about the rate of incarceration of young black men.

The presidential campaign that is now taking form may be the first contested nomination fight since 1892 without a Democratic candidate from the left -- and without any strong voice playing the traditional role of Democrats: questioning the status quo, defending the underdog, fighting the moneyed interests.

The thunder once heard from the left has been replaced by the silence on the left. The pressure from the Democratic left has been replaced by a vacuum on the Democratic left.

So far, the two Democratic contenders who could verbalize the old-time Democratic religion and mobilize the old-time Democratic coalition -- Rep. Richard A. Gephardt of Missouri and Sen. Paul Wellstone of Minnesota -- are skipping the race. The two candidates remaining in the field -- Vice President Al Gore and former senator Bill Bradley of New Jersey -- are in the moderate middle of the party, practicing a brand of politics that even their supporters acknowledge is as cautious as their personalities.

Unless the Rev. Jesse L. Jackson, a veteran of two presidential campaigns in the 1980s, decides to enter the contest, the 2000 campaign could signal three significant departures in American politics:

The Democrats could cede to the Republicans the populist impulse they have possessed since the days of William Jennings Bryan. The Democratic field today possesses no rousing populist speaker and no rousing populist ideas. There are plenty in the GOP, including commentator Patrick J. Buchanan. As a result the Democratic left, which traditionally has welcomed attacks on concentrated power and big corporations, is in danger of being eclipsed by the Buchanan right.

The tensions that defined the party throughout the 20th century -- between the theorists and the activists, between those who spring from the comfortable few and those who represent the striving masses -- could disappear. The interaction between Felix Frankfurter (City College '02) and Franklin Delano Roosevelt (Harvard '02) that helped produce the New Deal, and between Joseph A. Califano (Holy Cross '52, Harvard Law '55) and Lyndon B. Johnson (Southwest State Teachers College '30) that helped produce the Great Society, resulted in the yeastiest years of Democratic policy experimentation of the century. Now those tensions are being thrust in the background.

The nation may be on the verge of a new brand of middle-class politics that permits us to avert our eyes from the unpleasant sight of the dispossessed. In the past, presidential candidates spoke of the "forgotten Americans." Now even the politics of the forgotten Americans may become forgotten, at least for a time.

Democrats often paid a big price for veering left. With the exception of the Jimmy Carter years, Republicans controlled the White House from 1969 to 1993. Now the Democrats believe the road to the White House is really a path down the middle of the road.

That view troubles Mr. Jackson. He seems restless on the sidelines, though his ties to the administration and his role as Mr. Clinton's spiritual adviser might keep him there. "Working people looking for a fair shot and women fighting for equity and ethnic groups fighting for equal protection under the law -- that is the bedrock of the party," he said in an interview.

But the Democrats' two candidates seldom look left. In the last years they served together in the Senate, Mr. Gore recorded an average of 65 and Mr. Bradley 85 in the ratings by the Americans for Democratic Action, a rough measure of liberalism. (Sen. Edward M. Kennedy averaged 92.) Mr. Bradley once voted for aid to the Nicaraguan Contras.

Contrast that with the Democrats of years past. In 1912, Bryan introduced a resolution before the party convention opposing the nomination of any candidate "who is the representative of or under obligation to J. Pierpoint Morgan . . . or any other member of the privilege-hunting and favor-seeking class." It passed by a 4-to-1 margin.

Democratic operatives are relieved that the party seems planted firmly in the center, the better to fight a general election campaign in the fall of 2000. They may be correct. But the party that mounts that campaign in 2000 will be a different kind of party.

David M. Shribman is Washington bureau chief of the Boston Globe.