Rep. Harold Washington (D-Ill.), the Democratic mayoral candidate, today laid the blame for racial tensions here on President Reagan and made references to past medical and personal problems of Bernard E. Epton, his Republican opponent.

Epton opened a new chapter in this increasingly bizarre campaign Tuesday night when he admitted that he had been hospitalized twice, once in 1968 and then again for two weeks in 1975, for psychiatric tests.

But Epton also hit back at Washington, loosing a new attack on his opponent's integrity.

Washington, the first black to win a mayoral nomination here, told a labor gathering that he didn't blame Epton for "negative vibrations" of "the crudest sort" that are emanating from his campaign.

"In his cooler moments, he Epton is a rational man, but he is a clone of Ronald Reagan, who is orchestrating this thing," Washington said. "This campaign has been engineered by Ronald Reagan, conducted by Mr. Deardourff, and carried out by their willing flunky, Bernard Epton." John Deardourff is a Republican campaign consultant.

The use of the word "rational" was an allusion to the reports of Epton's hospitalization.

Epton, a state legislator, said he had the tests to learn if his chronic stomach pains were a psychosomatic illness and that he had been worried about family problems during the Vietnam war. He later learned that the pains were caused by ulcers.

The reports were damaging because Epton has maintained that his personal life is an open book, but he failed to mention any psychiatric treatment in a lengthy disclosure of health records several weeks ago.

Epton, in his attack, charged that Washington's record shows a "clear pattern of behavior, in matters large and small, that stretches over a period of 30 years." It illustrates a "disregard for the law" and a "failure to meet basic legal responsibilities," he contended.

Epton distributed court records alleging that Washington twice had his wages garnisheed for nonpayment of bills when he was a state senator and that he once told a judge he couldn't pay an $800 gas and light bill because he was unemployed. Washington was a member of Congress, earning $60,662 annually, at the time.

A spokesman for the Peoples Gas company, however, said company lawyers had erroneously included that allegation in a court plea and that it wasn't true. The bill, for utilities at a storefront campaign headquarters, was paid last winter.

In a debate last week Epton charged that Washington failed to file income tax returns for 19 years and was suspended from practicing law for 5 1/2 years because he accepted money from clients and then didn't represent them.

"Can a man who abuses the trust of his legal clients and who fails to pay his own bills be counted on to manage a city budget approaching $2 billion a year?" Epton asked.

Washington spent a month in jail on a charge of not filing tax returns for four years, and has made no secret of his financial problems. Today he got a big laugh at a corned beef and cabbage luncheon sponsored by the Chicago Federation of Labor when he said, "I've been paying my bills slowly all my life."

His integrity, however, has become a major issue, and his remarks today were seen as an effort to shift attention away from it and the race issue, which have dominated the campaign.

Washington contends that there is a "direct connection" between the Chicago mayor's race and the 1984 presidential election because both Democratic Mayor Jane M. Byrne and Epton "are Reaganites" who have "allied themselves with a man who has raped our cities and ripped Social Security."

"The last 16 days of this campaign to defeat Epton will be the first 16 days of a campaign to drive Ronald Reagan from the White House . . .and stop that Bob Hope-John Wayne syndrome Ronald Reagan is spreading around here like he is crazy," he said.

Reagan is orchestrating Epton's campaign, Washington continued, "but he is afraid to come in here himself . . . . I want to see him and Frank Rizzo in here so bad I'd pay for their plane tickets myself." Rizzo, a Philadelphia mayoral candidate, has criticized Washington and has voiced support for Epton.

But Washington reserved his harshest words for Republican adviser Deardourff, calling him "one of the slimiest, funkiest, low-life scurrilous individuals who ever crawled out from under a rock."

Deardourff's firm has produced television commercials urging voters to back Epton "before it's too late," a slogan Washington said "is a code word for racism , and it is echoing all over the city."

Epton, considered a liberal during his 14 years in the state legislature, has long been suspect by Reagan backers in Illinois.

No major outside GOP figures have campaigned here for him. And when the president visited Chicago for a fund-raiser for Sen. Charles H. Percy (R-Ill.) this winter, Epton was given a seat at the back of the room and his name wasn't even mentioned from the podium.