After 10 years of delay, the D.C. government yesterday started soliciting developers to transform a tawdry commercial strip along upper 14th Street NW into a new complex of retail stores, offices and high-density housing.

The city, hoping to revitalize a community left scarred and deteriorating by the 1968 riots, said it would sell nearly 12 acres of land along 14th Street, between Columbia Road and Newton Street, to the developer who can produce the best unified plan for the five-block area.

The city's request for development proposals specifically invited plans providing the "maximum economic benefit to minorities."

"In making such evaluations," the city proposal said, "the Redevelopment Land Agency will give weight to developers with a past record of meaningful minority participation."

The Safeway grocery store chain and Riggs National Bank already have said they plan to build new facilities in the redevelopment area, according to the city. Bishop Samuel Kelsey's Temple Church of God in Christ has proposed a combination shopping center and high-rise apartment complex.

In all, city officials said they envision a redevelopment project that would include 2 million square feet of retail and office space -- about one-third bigger than the Tysons Corner Shopping Center, for example -- and 700 to 900 housing units, most likely apartments.

The upper 14th Street area has slowly been rebuilt over the last decade -- "some progress, but not enough," as D.C. Mayor Marion Barry said yesterday in asking for the development bids.

"I know you've been promised and promised and promised to death," the mayor told about 50 community leaders at a streetside news conference, "We're going to rebuild this community. We believe in neighborhood revitalization and stabilzation."

During the last 10 years, 808 housing units have either been built or rehabilitated in the 14th Street Urban Renewal Area. Three parks have also been opened and several other renewal projects either completed or started, according to the city.

Commercial development has lagged. Numerous small businesses in the proposed redevelopment area have closed shop, leaving boarded-up store fronts as a reminder of the once-flourishing commercial strip serving the Cardozo neighborhood.

"It's difficult to remain optimistic. We have to, but it's a grind," said William H. D. Ellis, executive director of the 14th Street Project Area Committee, a community group that will review the development proposals along with city officials.

Ellis may have been thinking of the past as he introduced Barry. With rhetorical flourish, Ellis started to say "the honorable mayor, Walter . . ." before catching himself. Former Mayor Walter E. Washington went out of office last January.

Barry good-naturedly doubled over in laughter and told the crowd, "It's a good thing I've known him all these years. Otherwise he'd be in trouble."

Under the city's plan, it would sell five parcels on the west side of 14th Street, from just north of Columbia Road extending north to Newton Street, and the entire block bounded by 14th, Monroe Street, Holmead Place and Park Road.

The city now owns 10 of the 12 acres in the redevelopment area. City officials said the other two would be purchased if the winning developer needs the land to make a unified construction proposal. The two acres are in the middle of the redevelopment area, on the southwest corner of 14th and Park.

The 12 acres were appraised at $3,275,000 two years ago. But the city's asking price is likely to be substantially higher when the land actually is sold because inflation has drastically increased the value of almost all Washington-area property since 1977. In addition, Metro eventually plans to locate a subway stop at 14th and Irving streets although the station is not expected to open until mid-1989.