BOSTON -- He wouldn't be where he is today without her. Not in New Hampshire. Not in Iowa. Not in the running at all.

I don't say this as a political nicety, the words that any candidate would employ as he tipped his hat to a loyal wife. In the case of Gary Hart, it is the absolute truth.

Maybe this time he can do without the media consultants and campaign strategists and pollsters. But there is no way he can do without Lee.

So she can be seen these wintry days, standing by her man, in photographs and newsfilm, in the coffee shops and drugstores and high school auditoriums. They are inseparable. He even introduces her to the toll taker at a turnpike booth.

Lee Hart has become her husband's talisman. She is a portable shield against The Question, a living rebuttal to those who would attack him for wife misuse.

Who would be so rude as to badger him with questions about Donna in front of Lee? If someone in an audience or on late-night television criticizes his behavior as a husband, Hart has his defense close by. ''She's actively campaigning for me,'' he can and has said, ''. . . so I don't think this caller has the right to interpose himself in my wife's defense.'' If his wife doesn't feel abused, surely we shouldn't feel it for her.

Today Lee Hart holds the key to his comeback. And more than that. She holds the key to her own comeback as well.

Last May, when photographs of Gary Hart and Donna Rice seemed a permanent fixture in the papers, when everyone in America was speculating on the impact of ''womanizing'' in politics, the candidate's wife looked as if she were held together with chewing gum. She was the national image of a wronged wife.

Their marriage became public property. Many made bets on how much longer they would last. Three months? Twelve? People who had never met Lee Hart asked each other why Gary didn't just get divorced. People who knew nothing of their relationship asked each other why Lee didn't just ditch the guy.

When Lee Hart looks back to those days in May she says, ''It was hell,'' and nobody doubts it. But she chose to join her husband in portraying that hell as a media creation.

After 28 years of marriage and two separations, she said: ''I know Gary better than anyone else and when Gary says nothing happened, nothing happened.'' She was not a wronged woman. They were a wronged family.

When, in turn, Hart wanted to reenter the race, the decision hinged on Lee. As he put it coolly, ''It got down to how much abuse she was willing to take.'' Not from him, mind you, from the press.

Why did she do it? Why does she do it? Why does she shake hands every day with people who are often uncomfortable in her presence, people who shared her public humiliation, who see mental images of Donna Rice on her husband's lap when she comes into a New Hampshire hall? What makes Lee run?

I don't think it is masochism or unblinking ambition for the White House. If Gary Hart believes that he can overcome the image of philanderer and retrieve his dignity, I suspect that Lee Hart believes she can save her self-respect and her marriage. She can campaign as a partner, not a victim.

Her public image may have been as hard to live with as his. After all, we once applauded spouses for stoicism, for keeping a marriage together no matter what. Now we are as likely to wonder why someone ''takes it.'' Divorce was once a political kiss of death and indiscretions overlooked. Now we condemn infidelity and accept divorce.

Clearly this is not a Golden Era for wronged wives. We are less admiring of long suffering. We tend to believe that suffering and sufferers are foolish. We aren't comfortable with wives as victims.

But the woman Lee Hart tries to offer New Hampshire and Iowa, perhaps even herself, is not the wife left at home while her husband went cruising. She is, rather, the unflagging campaigner, the crucial member of the Hart team.

I don't know whether the voters will buy a new Hart brigade or a resurrected marriage. But for now, the candidate, a true loner, defiantly self-reliant and at times blindly self-centered, has taken on a real partner. This Gary Hart needs his wife. It must be, after all this, a good feeling for Lee.