Presidential elections are among the devices Americans use to prevent life from becoming dull, and the next one will be enlivened by a fellow who today is smack where he wants to be. He is in the Senate, leading a majority, handling a hot issue, on television. Tax reform and television are arriving in the Senate simultaneously: bliss it is this dawn to be Bob Dole.

Dole has, as successful politicians generally do, a talent for luck. He is reaping rewards from what other senators have sown.

Bob Packwood's work in the late 1970s as chairman of the Senate Republican campaign committee is one reason there is a Republican majority for Dole to lead. And now as chairman of the Finance Committee, Packwood has handed Republicans what many of them think is the galvanizing issue -- tax reform -- they need to keep control of the Senate in this autumn's elections.

The president, a.k.a. the Great Communicator, declared tax reform his top domestic priority, but failed to get the public excited about abstractions like ''simplicity.'' Packwood found something simple enough to arrest the public's attention: a number, ''27 percent'' -- the top of two rates for personal income.

The fact that tax reform will be debated on television with Dole literally front and center on the Senate floor is largely due to the efforts of former senator Howard Baker, Dole's friend and rival for the 1988 Republican nomination. Baker championed television in the chamber. Beginning in June, television viewers will see Senate floor action (and will learn that ''action'' is not always the word).

The pretense is that the presence of the cameras (they are rented and on temporary tripods) is just an experiment. The truth is the senators will remove the dome over the rotunda before they will remove the cameras. Even we who oppose the intrusion of cameras into a deliberative body must admit that the place looks splendid on the closed-circuit coverage already begun. For reasons relating to the size, color and lighting of the Senate chamber, it looks markedly better on television than the House does. It is an elegant sound stage for presidential campaigning.

David Keene, who worked for Reagan in 1976 and Bush in 1980 and now works for Dole, says: assume the front-runner, Bush, falters. Then Jack Kemp and Dole are the first tier, and Dole is better able to sustain a long campaign because he is at ease with a wider range of issues.

Also, Keene thinks ideology is often less important than cultural sympathies and antipathies, and Dole is culturally correct for the GOP now. Keene recalls a 1980 meeting on behalf of Bush with some bankers in Boston. They were passionately anti-Reagan -- but to the right of Reagan in their views. They were for Bush because Reagan gave them the willies: a Californian, an ex-actor, supported by all those small shopkeepers, he even ties his necktie in a Windsor knot.

One of Dole's defects (as a candidate, not as a public servant) is that he is so well thought of in Washington. Among senators and other prominent players he, along with Howard Baker, is considered the most qualified Republican. Still, he can survive the taint of Washington approval because, says Keene, Dole comes from the Midwest, the region ''most in synch'' with what the nation wants.

Furthermore, Dole has what football coaches call ''schedule luck.'' The Iowa caucuses come first and, because of the farming depression, ''Iowa is a foreign country.'' Reagan's popularity there is down. Dole should benefit from his strong identification with agricultural constituencies. Besides, Bush will have ''expectation problems'' because in 1980 he beat Reagan in Iowa (although with only 32 percent of the vote).

Sitting in shirt-sleeve comfort in the Majority Leader's Capitol office, with its unrivaled view of the Mall, Dole is looking in his mind's eye at a 1988 southern regional primary. He says his agricultural involvement, his military record and his wife (Elizabeth, the secretary of transportation, is from North Carolina) will help.

But when senators run for president by citing their laundry lists of votes for this and that, they lack a clear theme. Dole has a traditional conservative's (which means a non-neo's) dislike for the budget deficit. So when asked to distill Doleism into a single word, he says: ''solvency.'' Then he laughs.

He laughs a lot. He is the funniest -- make that the wittiest; others are funnier -- senator. But he knows it is cockeyed to think the electorate will rally 'round a banner bearing the word ''solvency.'' It might as well say ''oatmeal,'' which also is healthy but boring.

His theme will be ''leadership,'' sanctified by loyalty to Reagan. His 1985 rate of support for Reagan -- 92 percent -- was the Senate's highest. Leadership and laughter. Sounds like good television.