The adjective of choice for critics of George W. Bush's tax plan, heard repeatedly before, during and after Thursday night's television debate among the Republican presidential candidates, is "timid."

That may seem a strange description of a proposal that would cut taxes by more than $1 trillion over the next decade. Time was when $1 billion was an incomprehensible sum. Now some people speak of a figure 1,000 times larger as if it were peanuts.

But Republican politicians have made so many speeches about abolishing the Internal Revenue Service, scrapping the entire tax code and substituting a flat-rate income tax or national sales tax that Bush's trillion-dollar tax cut can be regarded, at least by some in his party, as "timid."

It occurred to me while watching Bush on stage for the first time with his five rivals that while that word hardly fits his proposal, it is not an entirely inappropriate characterization of the Texas governor's approach to this campaign--and perhaps to governing.

Let it be said at once that Bush emerged unscathed from Thursday's debate on WMUR-TV, the largest television station in the state whose first-in-the-nation primary on Feb. 1 looms as a large test for the early favorite for the GOP nomination.

He dealt effectively with repeated jabs from publisher Steve Forbes and counterpunched hard when Forbes tried to deck him on the dangerous issue of Social Security. Finding a 22-year-old Forbes column advocating the same gradual increase in the eligibility age that Forbes is now condemning Bush for acknowledging may be necessary was a way of telling his tormentor to "put a sock in it."

Nothing rattled Bush, and, in that sense, he dispatched the doubts that he is ready for big-league politics after only six years in state office.

But Bush notably failed to assert command of the evening or to establish a sense of presidential weightiness. Most of his answers were rote recitations of lines from his stump speech.

If the evening was a victory for Bush in avoiding any serious slip-ups, it was also a demonstration that the governor, far from fitting the image of assertive (not to say arrogant) Texans such as Lyndon Johnson and John Connally, is a minimalist in the art of campaigning and governing. As polite as his father, Bush seems to feel that the smaller the portrait he paints of himself, the better.

Now, timidity is not to be mistaken for lack of confidence. Bush is brimming with self-confidence. Early in his first race for governor, when few gave him much of a chance against incumbent Democrat Ann Richards, he told me--and anyone else who would listen--"I am going to be governor of Texas." Now he fully expects to follow his father to the White House.

But he does not intend to overextend himself in getting there. His rhetoric is modest. He may quote Pericles in a speech written by his advisers and carefully rehearsed beforehand, but on his own, he makes no effort to impress anyone. When asked in the debate about his reading habits, he mentioned four daily papers (from which he said he didn't learn much), one biography--and stopped.

The implicit question--Is that all there is?--applies to every dimension of Bush. His experience consists of six successful years, in prosperous times, as head of a state government where the power of the governor is constitutionally circumscribed. His agenda in Texas has been carefully chosen--and constrained. His single boldest proposal--a basic overhaul of the tax system to harness the revenues of the growing service sector--failed once in the Legislature and was never revived by Bush.

His mind is adequate but not subtle or active or particularly agile. He's offered a limited menu of ideas in this campaign. He makes the valid point that a president may be most effective when he husbands his political capital for a few initiatives, rather than involve himself in many fights. But for those--conservative or liberal--who yearn to see government in Washington break out of these years of gridlock in a big, bold way, Bush's incrementalism may be unfulfilling.

He has only one talent that is oversize. Sen. Judd Gregg, a member of a New Hampshire Republican dynasty who has been watching presidential candidates come here for four decades, says, "I have never seen anyone who can walk into a room and connect with people as readily as this fellow." That is indeed his gift, and in the current circumstances, it may well be enough to carry him to his goal.