These are Howard Dean’s “salad days,” whether by the dictionary definition of them as “the best time of youth” or the reference by William Shakespeare’s Cleopatra to “when I was green in judgment.”

His presidential candidacy, which he formally unveiled Monday after months of campaigning, is attracting far more interest than might have been imagined for the former governor of one of the nation’s smallest states. He recently drew an enthusiastic crowd of 3,000 in Austin, Texas.

But many top Democrats have expressed concern about the possible impact on their party if Dean of Vermont wins its nomination. Some fear a repetition of the electoral disasters of 1972 and 1984, when George McGovern and Walter Mondale each carried but a single state against an incumbent Republican president.

In his efforts to get attention, Dean has shown a propensity for loose talk that could make him a sitting duck for the relentless Bush political machine. He has expropriated without credit the late Sen. Paul Wellstone’s line about representing “the Democratic wing of the Democratic Party” and had to retract criticism of three rivals — Sen. John Edwards of North Carolina, Sen. Bob Graham of Florida and Rep. Dick Gephardt of Missouri.

On “Meet the Press,” he had difficulty explaining changes in his positions on the death penalty, which he now backs, and the balanced-budget amendment, which he once backed and on which he said he now goes “back and forth.”

In the process, Dean has transformed his image from skinflint centrist to pugnacious liberal by showing a zest for political combat against President Bush that delights Democratic audiences. But he also has gained a reputation for nastiness that could create problems.

Indeed, Dean’s candidacy is a reminder of Northern liberals’ poor track record as Democratic standard-bearers. The last one to win the presidency was John F. Kennedy in 1960. Besides McGovern and Mondale, two other Northern liberals also lost, Hubert Humphrey in 1968 and Michael Dukakis in 1988.

By contrast, the last two successful Democrats, Jimmy Carter and Bill Clinton, were Southerners opposed by many party liberals. Not only did both have experience as governors, they enjoyed some support in Southern and border states and from the party’s pro-defense wing.

Dean is a former governor, like four of the last five presidents. But the transplanted New Yorker’s experience in running the nation’s 49th most populous state pales alongside Graham’s in No. 4 Florida and Bush’s in No. 2 Texas.

The former Vermont governor deliberately has cast himself as the most dovish of the six major Democratic hopefuls, though he de-emphasized that this week. A perception of weakness on national security helped to beat both McGovern and Dukakis. And in the post-Sept. 11 environment, it could be a major problem for Dean.

Finally, it is hard to see how Dean could win the Southern and border states that were crucial in electing Carter and Clinton. Dean may be especially vulnerable because of his anti-war stance and his support of civil unions for gay couples.

He hopes to surmount those handicaps with a strong appeal to independents. But independents strongly backed the war against Iraq and Bush’s handling of the war against terrorism.

If past patterns persist next year, Dean had better enjoy his current celebrity and his victories in such meaningless exercises as the recent Wisconsin Democratic straw poll. He is likely to have fewer “salad days” in 2004.