When you don't like the way a game is played, you just change the rules. Such, at any rate, seems to be the maxim behind an effort to limit the number of years a person may serve as a member of Congress.

Such schemes have been advanced before, to no avail. But the latest version has drawn enthusiastic support from the Bush administration, and this suggests it could become a contentious issue in the next session of Congress.Would members of the House and the Senate endorse an amendment to the Constitution that would set the clock ticking on their own political careers? Don't be silly. Why cut their own throats? But they have been hearing an uproar all across the country this fall about how clumsily they are doing their job, and this has raised the idea that members should hold office only up to a fixed number of years, and then no more.

Who likes this proposal? President Bush, presumably. Vice President Dan Quayle recently talked it up as a way to shake up entrenched incumbents and encourage competition in elections for Congress. It was given another test flight the other day by none other than John Sununu, whom Sen. Bob Dole delights in calling the White House "chief of chaff. " George Bush may or may not have authorized their remarks, but we'll probably never know.

People who make their living by meddling with the Constitution have concocted all kinds of schemes to put a cap on the time members of Congress may serve. One current favorite seems to be a maximum of 12 years for members of both the House and Senate - in other words, no more than six two-year House terms, or two six-year Senate terms.

What gives this scheme more than academic interest is the rising public clamor for just such a brake on legislative power. Earlier this fall, voters in three states - California, Colorado and Oklahoma - approved ballot initiatives that limit the number of terms state legislators may serve. In addition, California voters cut into legislative pension plans, while those in Colorado voted to set a 12-year limit for members of Congress.

So clearly this is an idea with a bit of steam behind it. In the end, it probably won't fare any better than most attempts to tinker with the Constitution, especially since Congress itself is so skeptical. But the idea bespeaks widespread public gripes about the way some legislatures work, and this alone could give the plan surprising momentum.

To a GOP long squelched in its hopes for regaining House control, the term-limitation idea has understandable allure. By forcing scores of senior incumbents into early retirements, the plan theoretically would weaken the Democrats' grip on committee chairmanships and other positions of power. Republican and Democratic contenders for the opened-up seats could start from scratch - level playing field, and so on - and pretty soon there would be no long-entrenched incumbents with all their built-in advantages.

Even from a politically neutral good-government point of view, this has its appeal. Incumbents do have inordinate power against challengers. In some cases, as Quayle asserted the other day, "Americans are being denied competition in the electoral process."

What makes this plan so mischievous, however, is the damage it would do to the stability, continuity and institutional values that are a source of Congress' strength in the democratic process.

By automatically kicking members out when they reached their 12-year limit, voters would be foregoing some of the vision and seasoned judgment that often comes only with time. This seems a high price to pay simply for the knowledge that even the most inept legislator won't be around more than 12 years. You would force out the stars as well as the flops.

More to the point, however, is that voters, by arbitrarily limiting terms in Congress, are in some measure abdicating their own chance to choose between contenders. A ceiling of 12 years would probably tend to become the norm, with the interim elections made even less competitive than before because the 12-year clock would be continually ticking.

The result, in all likelihood, would be a Congress at once more static and less experienced than we have today. Further, because no incumbent member would ever have served longer than 12 years, there would be a pretty skimpy institutional memory. It would be a younger Congress, but also a Congress more volatile and more susceptible to public passions of the moment.

This is a needlessly risky way to improve competition in elections for Congress. One thorough round of campaign finance reform could reach the same end - without ripping Congress apart.