DETROIT (AP) _ The NAACP, which usually prefers to wage its battles in the courtroom and the statehouse, is taking to the streets to fight a series of Supreme Court rulings curtailing civil rights laws.

Leaders of the nation's oldest and largest civil rights group, which usually takes a quiet, behind-the-scenes approach, are angered by what they see as a judicial threat to 35 years of gains for black Americans.

For most of five days, delegates to the National Association for the Advancement of Colored People's 80th annual convention gave a polite and often enthusiastic hearing to a parade of Bush administration officials.

Vice President Dan Quayle and Bush Cabinet members Jack Kemp and Louis Sullivan pledged their devotion to civil rights, condemned racism and vowed to work to end the economic and social disparities between blacks and whites.

But the mood shifted dramatically as the five-day gathering drew to a close Thursday. Executive Director Benjamin Hooks, comparing the high court's conservative majority to the Ku Klux Klan, called for a ''silent march'' on the nation's capital Aug. 26.

''We're not going to let four men and a woman in black robes turn us around any more than we'll let white robes turn us around,'' Hooks said, referring to the garb traditionally worn by Klan members.

The convention also suspended its rules Thursday to condemn the high court and call for Congress to reverse the rulings.

One Michigan NAACP leader explained the contrast between the warm welcome for administration officials and the sharp attack on Republican policies and GOP-appointed judges.

''The NAACP is non-partisan,'' said Tillman Cothran, a professor of sociology at Western Michigan University and president of the group's Kalamazoo chapter. ''It is only natural that we would hear people from both sides.''

Cothran said he remains skeptical of the Bush administration.

''Gosh, we enjoyed hearing (Housing and Urban Development Secretary) Kemp saying, 'Stop exploiting poor people, stop discrimination against minority group members in housing,''' he said. ''We wait to see to what extent his department will live up to those words.''

The closing-day fireworks Thursday began with an address by Eleanor Holmes Norton, former chairwoman of the federal Equal Employment Opportunity Commission under President Carter.

Norton said blacks should give up on the ''Reaganized'' federal courts and put the heat on Congress and the president.

''To George Bush, we say, 'We're glad you're not Reagan, but that's not enough,''' she told the delegates.

The Rev. Jesse Jackson and national Democratic Chairman Ronald Brown challenged the notion that Bush differs fundamentally from his predecessor on civil rights.

''Reagan laid the tracks ... to take the rights of workers and women and African-Americans and Hispanics and the poor,'' Jackson said in the closing address Thursday night. ''Bush is putting grease on those tracks, not brakes.''

''I believe it's time,'' Brown said, ''that we tell George Bush, Dan Quayle, Jack Kemp, (national GOP Chairman) Lee Atwater and the rest of those Republicans, 'It's time to put up or shut up.'''

After listening to five days of speeches, Philadelphia delegate Gladys Wylie said the words from the Bush officials left her hopeful - but cautious.

''We think that this will be better than the Reagan administration for minority people, at least we hope it is, anyway,'' Wylie said. ''But it remains to be seen. You can get up there and say anything.''