Gary Hart is not doing justice to the cinnamon toast submitted by the Senate kitchen, perhaps because he wanted to be taking breakfast 16 blocks west. It is March 4, precisely one year since David Broder filed this lead paragraph to The Washington Post:

"Sen. Gary Hart (D-Colo.) won the Maine Democratic presidential caucuses tonight, dealing a serious and possibly fatal blow to Walter F. Mondale's pros pects for winning the nomination."

Today, Hart is required to think about Meeker, Rifle, Pagosa Springs and other Colorado communities. His term ends in 1986. In 1980 he barely won reelection (by fewer than 20,000 votes out of 1.1 million). If he runs in 1986, he will have to raise $3 million and work like a dray horse. And if he wins, which is far from certain, he probably will do so with no more than 53 percent of the vote.

After Hubert Humphrey lost the 1968 presidential contest, he went home and won a Senate seat. When Walter Mondale left the vice presidency in 1980, he decided against seeking a Minnesota seat in 1982 and instead became a professional Washingtonian. In 1984, that showed.

For a senator who has tried to become president, it can be hard to convince constituents that he still has his heart in being a senator. Hart seems to like the Senate and sounds mildly sincere when he says he prefers Georgetown, Colo., to Georgetown in Washington. But whether or not he runs in 1986, he will run in 1988.

In 1988, for the first time in 20 years, an incumbent president will not be in the contest. John Sears, a Republican strategist, notes that for 72 years, from 1861 to 1933, the GOP was considered the agent of constructive change, and Democrats elected only two persons president (Cleveland and Wilson). During the next 48 years, until 1980, the Democratic Party was considered the agent of change, and Republicans elected only two persons president (Eisenhower and Nixon). Sears believes that in 1988 the role of "agent of change" will be up for grabs.

Pat Caddell, a Democratic strategist, says that in 1988 the conservative surge will be a decade old. He dates it from 1978, the year five liberal Democratic senators were defeated. In 1978, the Kemp-Roth tax reduction plan was unveiled. Two years later, the Republican presidential nominee stood on the steps of the Capitol, with the Republican House and Senate candidates, to endorse the plan, which gave his campaign a theme and energy.

In December 1978, Democrats held a mid-term mini-convention in Memphis and Ted Kennedy spoke in praise of "sailing into the wind." His speech was a shot across President Carter's bow. Kennedy was making a thinly veiled threat to run against Carter if Carter trimmed to the conservative winds. Carter's reaction was to fight defections on the left by buying off interest groups, thereby embracing the notion that fidelity to Democratic principles means preserving all programs.

Hart's task in 1984 was to dramatize differences with both the Carter and Kennedy styles of liberalism. But the most telling contrast was between Hart's and Reagan's conceptions of what presidential campaigns should be. Their differences denote different ideas of democratic consent and leadership.

Hart is an issues-paper politician. He believes in dwelling on details, telling people the particulars of what he plans to do. He believes campaigns should produce consent to programs.

Reagan believes campaigns are to fill a reservoir of deference. (If the word "deference" grates on your democratic sensibilities, call it a reservoir of trust.) Reagan favors campaigns that set themes that bolster confidence in the theme-maker's character. His assumption is that the public's attention to politics is intermittent and its attention span is short. A constructive campaign convinces a majority that the candidate is a good fellow with a good idea of what he wants to do. These two perceptions by the public will translate into a lot of latitude for him when the game of governance begins.

Politicians, like the rest of us, tend to believe that the right thing to do is whatever they feel comfortable doing. This is in part because they, like the rest of us, tend to do well what they do comfortably. Hart, like most politicians, cannot campaign as Reagan does. Reagan's gift for rapport with the public is a rarity. For Hart, as for all who run in 1988, a crucial question will be: Has the public come decisively to prefer Reagan's conception of political leadership? Reagan may have created in the public a preference for a kind of campaigning that few candidates can master.