Democratic mayoral candidate Rep. Harold Washington (D-Ill.) unveiled a transition planning committee loaded with establishment names today as he opened his final drive in the April 12 election.

While Republican challenger Bernard E. Epton courted senior citizens and stopped in supermarkets along the lake front, where both sides say they think the swing vote lies, Washington vowed to "bring together the best minds from all corners of our city" if he becomes Chicago's first black mayor.

A Gallup poll of 1,007 voters, taken over five days ending last Wednesday and released tonight by the city's NBC television affilate and the Chicago Sun-Times, gave Washington a 51-to-37 percent lead, with 12 percent undecided.

It showed Washington receiving 92 percent of the black vote to Epton's 1 percent and receiving 20 percent of the white vote, about the minimum his managers think necessary for victory. Fully 16 percent of white voters said they were undecided, while only 7 percent of blacks polled were undecided.

The poll is consistent with reports from both camps that the race has become very tight.

Washington, a two-term House member, returned to his South Side congressional district tonight for ceremonies marking the 15th anniversary of the slaying of Martin Luther King Jr.

But even in an emotional setting created by the Rev. Jesse Jackson, Washington was deliberately inclusive in his appeal. Telling the black audience "we can be the healers, because we are the ones who have suffered from injury," he said, "I consider the unification of Chicago as my preeminent responsibility as this city's next mayor."

Epton, at a morning news conference, promised the elderly that as mayor he would create a one-stop service center for those with problems. But the heavier message came from Washington's midday news conference, symbolically held at the Bismarck Hotel, longtime headquarters of the city's Democratic organization.

Washington made public his transition committee, featuring some of the most prominent figures in the city's business, legal and academic establishment.

Serving as co-chairmen are Edwin C. (Bill) Berry, a respected black business executive and former head of the Chicago Urban League, and James J. O'Connor, president and chairman of Commonwealth Edison, the city's utility company.

Other nationally prominent individuals in the group include Borg-Warner Corp. Chairman James F. Bere, Northwest Industries Chairman Ben W. Heineman, publisher John H. Johnson, former secretary of commerce Philip Klutznick, former Federal Communications Commission chairman Newton Minow and Jewel Food Stores Chairman Donald S. Perkins.

Senior officers of two major Chicago banks were named to the fiscal planning panel, and big-name professors from the University of Chicago and Northwestern Univerity studded the list.

Underlining his message of reassurance that he intends to build a broad and balanced coalition, Washington said he is "not intent on seeking a wholesale replacement of people in city government. I am interested in continuity and reform."

He carried that message to the far North Side, visiting a vegetarian restaurant run by independent white political activists.

Michael Brady, the Democratic ward committeeman and a pre-primary campaign consultant to Democratic Mayor Jane M. Byrne, showed up for the event wearing a Washington button. But he was criticized by several other guests, who said his precinct captains were carrying Epton literature.

Brady said he thinks Washington, who won about one-fifth of the ward's vote in the primary, will do well to win half of it next Tuesday, despite its reputation as one of the most liberal white wards in the city.

While Epton was working the supermarkets in the same part of town, a reporter showed him a piece of literature he said was being handed out by precinct captains of veteran ward committeeman Vito Marzullo, one of the Democrats who has bolted to Epton.

The literature warned that "If you are white, and Harold Washington is elected mayor, get ready to move out of town."

Epton said, "I deplore this," and said he has issued instructions that his workers are to shun such appeals.