Here are the elements of a presidential candidacy bound to go nowhere: 1960s radical leftist. Lived on a kibbutz. Moved to Vermont in the tumult of 1968. Became a carpenter. Ran for governor twice and for Senate twice as a candidate for the socialist Liberty Union Party. Jewish — not an advantage in Iowa, New Hampshire or South Carolina. Would be 79 at the end of his first term. Bernie Sanders is not going to be president of the United States.

But that doesn’t mean he can’t be a big factor in the 2016 presidential race.

He polls about a third of the vote in New Hampshire, which, contrary to popular perception, is not very much like its neighbor, Vermont. (In northern New England folklore, adapted from Milton’s “Paradise Lost,” one state is full of the “parsimonious emmet,” the other populated by those known as “newts.”)

Mr. Sanders does less well in Iowa, though his iconoclasm suits the sort of committed liberals who participate in that state’s February caucuses — plus the United Auto Workers members who surely noticed that Mr. Sanders was swift to oppose the Trans-Pacific Partnership while former Secretary of State Hillary Rodham Clinton took weeks to decide.

This is not an argument that the Sanders surge threatens Ms. Clinton as she glides toward the Democratic presidential nomination. It is, however, an argument that he affects Ms. Clinton as she seeks the nomination.

This is all the more apparent now that it is also apparent that Sen. Elizabeth Warren of Massachusetts, the most prominent progressive in Washington, is not going to run for the White House. All the unrequited passion for Ms. Warren has been transferred to Mr. Sanders, with stunning suddenness and seamlessness. Earlier this month, the Ready for Warren group endorsed Mr. Sanders, saying he was the candidate “who best embodies the values that Warren champions.”

Now we confront the nature of the Clinton campaign. It is fueled by determination rather than passion. There’s nothing romantic to it, aside from its historical significance as the vehicle for the first female presidency — a factor not to be underestimated in November but less powerful now. Her steady-as-you-go campaign is the political equivalent of the line from the English novelist George Meredith that, a generation ago, was emblazoned on thousands of trivets hanging on kitchen walls, tacked against the rice wallpaper: “Kissing don’t last, cookery do.”

Ms. Clinton, the candidate of the cookery, is running the campaign of the hot tuna casserole. Mr. Sanders, by contrast, is running the campaign of the moonlight smooch.

Yet the Clinton campaign must deal with the factors that make all those hearts flutter there by the shore of Lake Winnipesaukee or by the Raccoon River in New Hampshire, for Mr. Sanders, who by appearance — floppy white hair, rumpled suit — does not exactly possess the raw materials (or the raw energy) that customarily make the masses swoon. He’s no Edward Rochester of “Jane Eyre,” nor even Heathcliff of “Wuthering Heights.”

But the danger for the Clintonistas is that by its very existence, the Sanders campaign reveals the character of the Clinton campaign.

While the Sanders campaign is supple, the Clinton campaign is clunky. The Sanders campaign is ruled by instinct, the Clinton campaign by calculation. The Sanders campaign is audacious, the Clinton campaign is cautious. The Sanders campaign is roses and chocolates and chilled Champagne and a hopelessly amorous stroll across pine needles through thick woods at dusk (we’ll find our shoes later), while the Clinton campaign is geraniums and rice pudding and V8 juice and a station-wagon trip across Interstate 80 (we’re wearing sensible shoes, double knotted).

The strong likelihood that the Clinton campaign will triumph is important but, at this stage of the race, almost irrelevant.

Because it is Mr. Sanders (like Ms. Warren before him) who has the whip hand. By not winning he may still prevail, in the way that Ms. Warren did on income disparity. Just as Ms. Clinton embraced the signature Warren message by characterizing her campaign as an effort on behalf of “everyday Americans,” she also sought to embrace a principal Sanders message by saying, finally, that she opposed the Trans-Pacific Partnership, which she repeatedly supported while a member of the Obama administration.

The next issues to watch for the Warren/​Sanders effect: Single-payer health insurance, student debt, Wall Street, fracking.

We know what Mr. Sanders believes and we know he will say almost anything. We’re not quite sure what Ms. Clinton believes, but we know that she will fashion her remarks with craftswoman-like care. People probably want the latter in a president. They’re drawn to the former in a primary campaign — which is why, in New Hampshire in 1984, Sen. Gary Hart of Colorado, whose very eyes transmitted a twinkle of romance, prevailed over former Vice President Walter Mondale, whose fundamental decency suggested he was a fuddy-duddy and whose native caution suggested he was rigidly conventional.

All of which brings us to the most natural Bernie Sanders analogue, the 1992 Republican struggle mounted against George H.W. Bush, who held the presidency, by Patrick J. Buchanan, who in New Hampshire held a pitchfork. Mr. Buchanan had more fun, was more unpredictable, had better lines (“All the knights and barons will be riding into the castle pulling up the drawbridge in a minute. All the peasants are coming with pitchforks.”) Mr. Bush had better results, though he lost the general election to Mrs. Clinton’s husband.

“I pulled Bush to the right on social and cultural issues, and he stopped talking about the New World Order,” Mr. Buchanan said in a telephone conversation last week. “I like Bernie — especially his independence — and I think he can have the same effect on Hillary, moving her way to the left.”

Mr. Buchanan didn’t win a single primary or caucus in 1992, though he came within 16 percentage points in New Hampshire (and actually won the primary there four years later, edging Sen. Bob Dole by one percentage point.) But he had a blast, and he didn’t allow Mr. Bush to wobble toward the center.

Similarly, Mr. Sanders will very likely win no primaries next year either. But Ms. Clinton will feel his presence at every stop, in every state.