WASHINGTON — It brought down a President, spawned an assertive mood in Congress, fostered a new generation of political leaders, brought about an array of reforms in government, altered American journalism and set a benchmark for subsequent political scandals.

In short, the Watergate scandal radically transformed American politics.

Yet many of the changes wrought by what began as "a third rate burglary" on June 17, 1972, appear to be evaporating. Twenty years later, the legacy of Watergate is becoming blurred by new political developments and a fading national memory.

President Richard M. Nixon, who resigned in disgrace, is working tirelessly to rehabilitate his reputation. The idealists who were drawn into government after Watergate either have become part of the Establishment or have left Washington.

Congress is on the defensive once again, struggling to overcome a series of minor scandals. Journalists are being accused once more of focusing too much on frivolous matters. And many of the sweeping legislative changes brought about after Watergate--such as the War Powers Act, the congressional budget process and limitations on campaign contributions from special interests--are no longer viewed as effective.

In addition, many younger people now in government--such as 30-year-old Rep. Jim Nussle (R-Iowa)--have no personal recollection of the lengthy congressional hearings, the categorical denials from the White House, the Supreme Court's momentous decision requiring Nixon to surrender his secret tapes, the President's tearful farewell or the conviction of many of his former aides.

To politicians and political scientists alike, it now appears that one of the few enduring results of Watergate may be the distrust it spawned among Americans about their government. "Watergate generated an attitude of cynicism and mistrust that remains with us today," said Watergate historian Stanley I. Kutler.

In 1992, that distrust is once again fueling sentiment for reform in Congress and, in addition, creating support for billionaire Ross Perot's protest candidacy for the presidency. Two decades after Nixon's men broke into the offices of the Democratic National Committee in a building named Watergate, the nation appears to be on the verge of yet another political upheaval that could set new rules, just as Watergate did.