Now that Sen. Gary Hart (D-Colo.) has jumped most of the way into the 1988 presidential primary race, and Sen. Edward M. Kennedy (D-Mass.) has yanked himself all the way out, some folks are calling Colorado's retiring senator the front-runner.

He'll have nothing of it.

"I am not in that position," Hart said, surveying his political prospects by the fireplace of a cozy 90-year-old stone and log cabin he recently bought in the jagged Rocky Mountain foothills just west of Denver.

"I am not going to have a big bank account. I am not going to have lots of endorsements."

Hart spoke almost longingly, as if by some act of personal handicapping he might turn himself back to his pre-1984 incarnation, when as a little-known insurgent he came roaring out of a big Democratic field, nearly wresting his party's nomination away from heavily favored former vice president Walter F. Mondale.

Yes, he grudgingly conceded, the contest will be different in 1988. Yes, it will now be a debate among "new generation" Democrats, among whom he is -- no sense denying it -- now the best known.

And yes, he insisted, he is "comfortable" with this new station, even if he draws the line at assuming the dreaded mantle of front-runner.

"I don't mind the respectability," said Hart, who, at age 49, has spent much of his political career criticizing his party's establishment. "It will give me an opportunity to get across my message. I welcome that."

How Hart can engineer this transformation -- part psychological, part political -- from party renegade to leader of a newly configured Democratic establishment is probably the most compelling question in Democratic presidential politics over the next two years.

His detractors say they think that Hart is too aloof and iconoclastic a politician to take advantage of his new opportunities. His supporters here disagree.

"I saw him do the same kind of thing to win a second term in Colorado," said Hal Haddon, a Denver lawyer who managed Hart's two Senate campaigns. "You wouldn't believe the way he went out and lined up political support among some of these small-town mayors."

Still, Haddon is not completely happy with Hart's new perch. "For the sake of posturing, I'd just as soon have Teddy Kennedy in it," he said. "Then we could do the Mondale thing all over again."

Hart appears to have anticipated the new challenge long before it was thrust upon him. Almost since the day after the election, he has been painting himself in more conventional tones than he did as the "new ideas" candidate of 1984.

"In resisting protectionism, the foolishness of Gramm-Rudman and the injustice of Reaganomics, I've tried to uphold my party's principles when some Democrats were abandoning them," Hart said in a speech Saturday, when he bowed out of a third race for the Senate and declared his "interest" in the presidency.

Later in the interview here on Troublesome Gulch Road, he called himself a "traditional Democrat" and seemed to champ at the bit to get into a debate with other prospective "new generation" presidential candidates over proposals that stray from Democratic Party orthodoxy, such as Arizona Gov. Bruce Babbitt's call for a means test for federal entitlement programs. "Now is not the time," he said, catching himself.

Last year, Hart called for a compulsory national service, either military or civilian, for young adults (he now says the program should be voluntary at the outset) -- hardly the kind of proposal one would identify with the 1984 champion of the young and libertarian voters.

Talking by the fire, Hart went out of his way to mention he had had lunch last year with AFL-CIO President Lane Kirkland. And he said that if he is a candidate in 1988, he will go after the very interest group endorsements -- including labor's -- that he pilloried Mondale for taking. The distinction, he said, is that he won't overpromise.

Many are skeptical about how well he can manage these shifts of tone. "I'm not sure he realizes how much some of these labor guys hate his guts," said Paul Tully, Mondale's political director in 1984.

"He still hasn't found a way to convince rank-and-file Democrats -- labor, elderly, women, blacks -- that he feels and cares for them," said Paul Maslin, who did some polling for Hart in 1984.

Hart admits to no calculated recasting of his political persona. He said his "basic themes" in a 1988 presidential campaign would be similar to those of 1984: modernizing the nation's economic base, job retraining and military reform. He is about to publish a book entitled "America Can Win."

This spring he will deliver a series of lectures on a new Democratic Party foreign policy.

"I don't think those of us Democrats who came into politics in the 1970s have quite articulated or worked out our foreign policy," he said. "About all I was able to articulate in 1984 was that we shouldn't go to war in the Persian Gulf for someone else's oil when we didn't need to and we shouldn't go to war in Central America over the Sandinista government -- a whole bunch of shouldn'ts." He said he will try to define where this country should be prepared to defend its interests with force, in an effort to address the charge that his party is "soft on communism."

Hart said he will make a final decision about running for president sometime after the November election. If he runs, he said he expects to base his campaign in Colorado, which would have "symbolic" advantages over Washington.

"I wouldn't run as an anti-Washington candidate, though," he said. He said he is not running for reelection to the Senate because "you can't do both run for president while serving in the Senate and do them right . . . . It would not be fair to Coloradans."

However, one close political associate, who asked not to be identified, said Hart's reasoning on the Senate race was more defensive:

"Gary knew he would be the No. 1 target of the national New Right if he ran again this year, and he knew that if they saturated a small state, they could do a lot of damage. He saw what [Sen.] Jesse Helms [R-N.C.] did to a good man like [then-governor] Jim Hunt [in the 1984 North Carolina Senate race]. He didn't want to risk the same thing happening to his career."

If Hart is wary of letting an opponent beat him up, it is understandable. Most analyses of 1984 say he lost the nomination fight, after having come so close to winning, when he permitted Mondale to frame the "Who is Gary Hart?" question in a way that played on voters' uncertainties about where he came from, what he stood for and even how old he is. "I don't think Gary faces a fatal character question, like a Chappaquiddick, but it's one he'll have to address," Maslin said.

Hart dismissed that analysis, tending instead to look to mechanical matters -- the shape of the election calendar, inability to file delegate slates at the right time in key states -- as the best explanation for his defeat.

"I could just as plausibly argue that if [Ohio Sen.] John Glenn had not decided after New Hampshire to go to the banks and borrow $2 million, enough Glenn votes would have come to me in Georgia and Alabama, and that would have been it. I had no control over John Glenn . . . . There were a lot of reasons that I didn't win that I had no control over," Hart said