Democrat Michael Dukakis spent Friday at his wife's side as she recovered from a delicate spinal operation, and Republican George Bush returned to Washington to welcome President Reagan home from Moscow.

Jesse Jackson, the only candidate out on the campaign trail, called for an end to discrimination against AIDS victims as he searched for votes in Tuesday's final four primaries."We cannot wait to lead our nation away from discrimination and fear-mongering. All leaders must speak out now," Jackson said in a statement in Los Angeles. "The president must take every available step, including an executive order, to stop discrimination now."

Dukakis is favored to best Jackson in Tuesday's balloting in California, Montana, New Jersey and New Mexico and seal his hold on the Democratic presidential nomination.

The Massachusetts governor continued to pick up delegates from uncommitted blocs and those pledged to candidates who have dropped out. By late Friday, he was about 300 delegates short of the 2,081 he needs to win the nomination in Atlanta in July. Tuesday's primaries have 466 Democratic delegates at stake.

Dukakis canceled his campaign schedule Thursday to return to Boston after doctors urged immediate surgery for his wife Kitty. He spent the night at Massachusetts General Hospital and then worked at the hospital awaiting the end of the operation.

After five hours of surgery to correct a neck problem that doctors feared could lead to paralysis, the prognosis was positive.

"The operation went very well," said Dr. Lawrence Borges. "There were no problems at all."

Doctors removed two herniated discs from her neck and replaced them with bone taken from her hip. She had been experiencing pain and numbness for several weeks and doctors determined both problems were caused by dangerous pressure on her spine caused by the discs.

"I talked to Kitty in the recovery room and she said she wanted an ice cream and a massage," Dukakis said following the surgery. "I'm prepared to provide both."

Dukakis said he would resume campaigning in New Jersey over the weekend, if Mrs. Dukakis' condition remained good, and head to California for a final campaign swing on Sunday.

Bush, the GOP-nominee-to-be, returned to Washington from a week of meetings at his Kennebunkport, Maine, to be part of the entourage welcoming President Reagan home from the superpower summit.

But first he flew by helicopter to Walter Reed Army Medical Center to visit Salvadoran President Jose Napoleon Duarte, who is suffering from stomach and liver cancer.

"I plan to wish him well and share our country's appreciation for all he's done for democracy," Bush said before the half-hour visit.

With the primaries almost over, Dukakis began to muse a bit about the process of picking a running mate.

In an interview aboard his campaign plane heading back to Boston Thursday evening, he said 1984 Democratic nominee Walter Mondale advised against following his example of a public series of interviews with possible running mates. Dukakis said he was taking that advice to heart.

"I doubt very much I will do that," he said.