"MY QUESTION to you," said Bill Bradley in his debate with Al Gore on Wednesday, "is why should we believe that you will tell the truth as president if you don't tell the truth as a candidate?" Sadly, something like this question could be directed at most of the presidential aspirants in both parties, including Mr. Bradley himself. The campaign usefully airs issues of policy and character, but it has a way of demeaning contestants.

Mr. Bradley's assault was prompted by his opponent's numerous attacks on him, which collectively do amount to dishonesty. Mr. Gore has decried the Bradley campaign's proposed extension of health coverage to uninsured Americans as overly ambitious, a charge that is at least plausible. But he also has attacked Mr. Bradley from the opposite direction, accusing him of indifference to the health care of precisely the lower-income families the Bradley program seeks to help, as well as minorities. While slurring Mr. Bradley's ideas and motives, Mr. Gore preaches that he has never attacked his opponent personally. Then, when Mr. Bradley hits back at him, Mr. Gore scolds his opponent for going negative.

Nor is Mr. Bradley above criticism. He began his campaign promising a different kind of politics, free of pandering and attacks. Yet now he is in attack mode; and in the run-up to the Iowa caucuses, he pandered hard to the farm vote. In an earlier debate, Mr. Gore attacked him for not voting for an especially generous flood-relief amendment. That was an opportunity for Mr. Bradley to celebrate principled resistance to special interests. But Mr. Bradley mumbled a disclaimer rather than summoning the courage to defend his own record.

The Republican contest has been less obviously demeaning, partly because of the larger cast of candidates. But the same tendency toward dishonesty is evident. Out on the stump, George Bush throws out numbers suggesting, preposterously, that his tax cut would consume only a quarter of the projected surplus. The truth is that it would consume upward of $1 trillion over 10 years, more than the entire non-Social Security surplus if you assume that spending will keep pace with inflation. John McCain, generally a truth-teller, has fudged his views on the Confederate flag in order to appease South Carolina primary voters. Steve Forbes, once a moderate on abortion, has opportunistically changed into an opponent of abortion rights.

Up to a point, the candidates' dissembling may be dismissed as the product of election pressures, with honesty reasserting itself after the campaign. Orrin Hatch seemed instantly more attractive when he withdrew from the Republican primaries on Wednesday; he suddenly gave up boasting, and instead told self-deprecating jokes. Yet the worry is that the candidates' response to election pressures may heighten voter alienation and inflict damage that outlasts the campaign itself.