Some of tomorrow's candidates have been campaigning for years. The more candid among them might even admit that a politician never stops campaigning.

Politicians, like actors, are almost always "on camera," and as soon as one performance is finished, they begin rehearsing for the next one.

After a while, a voter with a low threshold of pain begins to wonder whether there ever will be an end to the noise. The poor voter has about as much chance for peace and quiet as an insomniac who lives in an apartment next door to Mick Jagger.

Tomorrow we'll get a brief respite from rhetoric.But by Thursday, the guest speakers at the National Press Club luncheon will be some of the nation's best politician-watchers. Their assignment will be to begin the next campaign by analyzing, interpreting, explaining and arguing about this one.

The only thing sure about the 1980 results is that about half of us will be dissatisfied with them. It is also a good bet that whoever is elected president will, by 1984, be wondering: "If I won and he lost, how come he looks like a million dollars and I look 20 years older?"

One reason may be that nothing is required of a challenger for office except that he be a perceptive critic, whereas an incumbent is expected to solve insoluble problems. That can age a man rapidly.

A challenger can ask his audience, "Do you think we'd have been in this mess if our party had been in power?" The audience will always roar, "No!"

Nobody ever stands up and asks, "How could we have avoided the mess? What should have been done?"

Inflation is an excellent example. For numerous and complicated reasons, inflation has for a long time been affecting our national economy. In recent years, inflation has escalated. To eliminate or even diminish it, national policies of long standing would have to be reversed.

Yet during this past weekend, Gov. Reagan again asked whether inflation would have risen to 18 percent under Gerald Ford, and his audience as usual roared back, "No!"

Nowhere was a voice raised to ask, "How would Jerry Ford have stopped a process that had been going on for decades? Would Ford have asked Congress to cut federal spending in half? Would Congress have obeyed? Would it have raised income taxes by 50 percent or taxed gasoline by 50 cents a gallon? Would Ford have imposed wage and price controls? Would Ford have attempted to intrude upon the autonomy of the Federal Reserve System or its control of the supply of currency in circulation? Would Ford have fought inflation by making borrowing easier rather than more difficult? Would Ford have banned cost-of-living increases on the defensible grounds that they exacerbate inflation? Would Ford have defied labor unions that asked for raises for their members?"

No, I think it is clear that the things that cause inflation and keep it burning ever more fiercely are not things a president can turn off at will, even if he is brilliant, charismatic, astute, resolute, persuasive, omniscient, a born leader, brave, clean, reverent or even reborn -- attributes to which men like Carter, Reagan and Ford have no clear claim.

Inflation's roots may lie in public pressure for government programs that attempt to do too much, waste within the government, fraud against the government, individual expectations of upward mobility, diminishing productivity and the demand of low-income workers for ever-larger pieces of the economic pie. Other factors may also be involved, although our economists don't always agree on what they are.

But even if our sages were in complete agreement about the nature of the malady, it would not be politically feasible for a president or a Congress to push through policies that are opposed by so many millions of voters. And even if a dictator took power and forced the country to adopt unpopular reforms, there is no assurance they would work. Dictators and planners are often wrong.

I am not yet sure against whom I will vote because I have been subjected to so much advertising hype and crafty rhetoric. I keep trying to remind myself that an election is not a popularity contest. It won't make a bit of difference whether I'm fond of the fellow who will fly this airplane or whether I dislike him intensely.

All that will matter will be: Is this the guy who is best qualified to get me there in one piece?"