Saying he appeared to offer the country "coal" while President Reagan was "handing out rose petals," Walter F. Mondale said that his failings contributed significantly to his landslide defeat last year and expressed resentment toward the Rev. Jesse L. Jackson for making "life quite difficult for me."

"I tried to treat the first black candidate for president of the United States with dignity and to accept the seriousness of that candidacy, and I believe that was right," Mondale said in an interview with The Washington Post. "I don't believe that Jesse treated me in an equivalent way."

Mondale, marking his reentry into the practice of law with a round of newspaper and television interviews, said he thinks that his 49-state loss "will hold up well in history" because "I told the truth . . . , and it's becoming obvious." He called the GOP's gains temporary and predicted problems for Republicans when "the chickens come home to roost."

The interview took place the morning after Reagan and Senate Republicans agreed to a budget package that includes a cap on Social Security cost-of-living increases. With obvious relish, Mondale showed up for the interview brandishing a page of the transcript from his first debate with Reagan in which the president promised he would "never stand for" a reduction in Social Security.

But the former vice president, tanned from a skiing vacation and preparing for an overseas trip as a partner in the law firm of Winston & Strawn, acknowledged that marathon campaigning had left him "exhausted, bone tired" and that its end had brought "tremendous relief" and disappointment.

"There's no question that history will record that I took a helluva shellacking," Mondale said.

"Now I think there's a lot of things I'm going to be blamed for, and many of those criticisms I accept," he added. "I think if you look at the campaign in retrospect, I looked like a person who was always talking about problems, about tough steps that were needed to solve problems.

"While my opponent was handing out rose petals, I was handing out coal. Someone said that he called for change without mercy and I called for mercy without change.

"You know, I've never lost young people before," Mondale said. "I did not communicate hope and opportunity and change, even though that's what I was saying. That's not what they heard, and I'm responsible for that."

Mondale had kind words for Sen. Gary Hart (D-Colo.), his chief competitor for the Democratic nomination.

"At the convention, he was the first to come to me and sign up," Mondale said. "He did everything he could to produce a successful convention, and he went out of that convention and he did everything he could for me in that campaign."

But asked whether he should have handled the challenges from Jackson differently, Mondale replied in tough and measured terms. "I am not happy with the situation at all," he said. "Whether I could have handled it differently, I don't know."

Mondale, who sought to avoid confrontation with Jackson throughout the campaign, continued: "I earned my spurs in the civil rights movement. All my life, not for political but for religious reasons, moral reasons, that's where I've been, and I'm proud of it, and I'll always be there. He Jackson did not accept that, and it made life quite difficult for me."

Mondale acknowledged that despite his efforts to distance himself from some of the most controversial aspects of Jackson's campaign, including statements by Nation of Islam Minister Louis Farrakhan, "there was some residual feeling in this country that Rev. Jackson would have more influence than he would have had, and I think it hurt."

Asked what role he sees for Jackson in Democratic politics, Mondale said, "Oh, that's for him to decide. But I think he's got to do some thinking about how he intends" to proceed.

Mondale expressed no regrets over his choice of former representative Geraldine A. Ferraro (D-N.Y.) as his vice-presidential running mate and said that waiting a few more days to look over the finances of Ferraro and her husband, John Zaccaro, would not have prevented the controversy over their tax returns.

"I'm satisfied that she leveled with me," he said. "I'm very grateful to Gerry. She campaigned very hard. She was a spirited partner. I think as a matter of fact that if you look at the last six weeks of that campaign, she did a better job than her opponent. And I have nothing but gratitude for her."

Mondale said that despite Reagan's victory and polls showing gains by the Republicans, "I don't see any realignment at all."

Nonetheless he encouraged Democrats to "listen to every conceivable kind of analysis" and to "look at new faces that have never been considered before for president and other offices."

He singled out the new Democratic Leadership Council, formed mostly by southern and western elected officials and seen by some Democrats as a threat to Democratic National Committee Chairman Paul G. Kirk Jr.

"I don't think we should object to that at all," he said.

But he praised Kirk as well. "I think that Paul will prove to be a good chairman," he said. "I think he's proving it already."

Mondale, interviewed in the board room of Winston & Strawn, sprinkled his analysis of the campaign and the Democratic Party's future with good humor.

When he learned that a photographer had come to take pictures, Mondale, holding a long cigar, uttered an expletive and refused, as he had done throughout the campaign, to be photographed with the cigar.

"My wife says it makes me look like a politician," he said.

For the rest of the 60-minute interview, the cigar sat in an ashtray on the table.

Friends say Mondale is enjoying the role of a private citizen, including the stir he causes when he flies coach on commercial airlines.

He also responds with some bemusement to compliments about his campaign from strangers. He has told friends that there are two types of people he knows did not vote for him: those who say he ran a great campaign and those who tell him no one could have beaten Reagan.

Mondale repeated assertions that he will not run for public office again and that he is excited about his "new life" as an international lawyer. His first trip will be to England, Finland, Norway and Greece.

"I will not lobby. I will not be an influence-type lawyer," he said. "I'm a professional lawyer."

At the same time, he said he will be an "active Democrat," writing and speaking on issues and working for candidates if they ask him. But he said he has no plans to endorse a Democratic candidate for president in 1988 before the national convention.

Mondale said he deliberately had taken nearly half a year before embarking on his new career.

"Because I'd been through it losing and because I've seen friends who did it, there were a couple things that I knew I had to do," he said. "Number one, I had to make a hard choice on whether I was going to seek office again -- to go back to the Senate or run for the presidency. And I made a hard choice not to do that because if you don't get that out of you, you can't plan your life. The second thing, you can't bear grudges. I'm not going to write a book to settle old scores; I'm not going to do any of that."

Of his decision not to seek office again, Mondale said: "I've been at this for over two decades, and I didn't want to be a perennial, uh, uh." He could not bring himself to finish the sentence.

Even months after the campaign, Mondale sounded weary when he looked back on it.

"This was a tough nominating campaign and a tough campaign," he said. "Toughest ever. And I had to sustain a level of interest, attention and energy even though it was clear to almost everybody that I was almost certainly going to lose. And boy, that takes a lot out of you."

But with relief came disappointment and, according to friends, a difficult period for Mondale.

"I wanted to win," he said. "I thought I could be a good president. I thought I was right on the issues. There are some things I feel very deeply about that I think this administration is destroying in American life, at least temporarily, and some dangerous things internationally.

"And I lost, and it's an election with a lot at stake. He will now get the Supreme Court for sure," Mondale said. "He will be able to carry on a lot of the dismantling of programs that I feel deeply about. His retreat on civil rights and women's rights is profound. This 'Star Wars' stuff is very, very dangerous. And he will be able to succeed in a lot of that."

But as he noted in his news conference the morning after his defeat, Mondale said he never doubted he was running uphill.

"We were running at a very inopportune time against a very popular incumbent when the nation starved for continuity with the economy performing well and international problems more or less off the stage at the moment," he said.

Mondale has said before that part of his failure was his inability to communicate through television. "I'm not trying to excuse what happened in '84 on the basis of television technique," he said, "even though I think Reagan's a genius at it and I'm not very good at it.

He mentioned Reagan's appearance at the Summer Olympics. "I'm the guy grinding away on civil rights and women's rights; he's the guy taking the flag from me. He's very clever. He handled that, and I just wasn't in that ballgame."

Mondale conceded he made tactical errors in the campaign but said his call for raising taxes was not one of them.

"I've been around politics a long time. I knew what I was saying there," he said. He also said he wanted to have a "mandate" to raise taxes if elected, adding that he thought the statement put Reagan on the defensive.

"We had them for a month," Mondale said almost gleefully. "It was clear they were planning to raise taxes and I'd caught them" by asserting Reagan had a "secret plan."

Mondale said, however, that he should have placed more emphasis on tax simplification, an issue then identified strongly with two Democrats, Sen. Bill Bradley (N.J.) and Rep. Richard A. Gephardt (Mo.), and now supported by many Democratic leaders as well as Reagan.

The Minnesota Democrat, raised in the farmer-labor traditions of his party, said he did not regret endorsements he received from labor unions early in the campaign for the Democratic nominations. Many critics have said the early endorsements contributed to the perception of Mondale and the Democratic Party as captives of special interests. Kirk has asked the AFL-CIO not do the same in 1988.

"I think my defeat had nothing to do with that," Mondale said, although he allowed that some voters might perceive the quest for such endorsements as being "rigged and the American people aren't involved in it."

Mondale argued forcefully, however, that the voices of labor, civil rights groups, women and environmentalists were legitimate in a political arena "fraught with pressures from every conceivable source, perhaps the most overwhelming of which is the growing influence of special-interest PAC political action committee money."

"How in this system of pressure does the public interest really get served?" he asked. "Right now, the one interest that's being served is big money. And if you remove these other things, they'll really run the show."

He seemed less self-assured, however, about the other choice he announced before the convention -- that of Georgia Democratic Party Chairman Bert Lance to be national party chairman, replacing Californian Charles T. Manatt, whose relations with Mondale were strained.

"I really regret that, especially because I hurt a friend of mine, Bert Lance," Mondale said of the decision. "I thought that it would work, and the reaction surprised me. Maybe it shouldn't have, but it did . . . . The timing was bad as well, but that's just a sideshow."

The Lance controversy hurt Mondale, especially in the South, where he had hoped that the Georgia banker would improve his chances. Mondale's first trips after the convention concentrated on the South and drew criticism from some who considered a Democratic victory there a long shot and urged that he concentrate on his base in the Midwest and Northeast.

Mondale expressed no regrets about that strategy, saying that while it risked a loss of base support that could lead to an overall rout -- which it did -- it also offered "a reasonable hope of victory."

Mondale said he came out of the campaign with a sense of gratitude.

"When I was a young man, I used to dream maybe someday I could be an alderman," he said. "Instead of that I became an attorney general, a senator, a vice president, a Democratic nominee. And I had opportunities and experiences and a chance to be at center stage in this country rarely experienced by anybody. I'm grateful for that. I rejoice in that. The American people have been very kind to me -- and are."