George Mitchell and David Emery, the candidates for the Maine Senate seat, each bought an ad on the local broadcast of the seventh game of the World Series. Emery was on after the second inning, when all we wanted to know was which team would break out on top. Mitchell came on at the end of the sixth, when the Cardinals had just erased Milwaukee's brief lead.

The candidates should have saved their television money. On this night of baseball drama, their ads were more than irrelevant; they were intrusive. The lighthearted Miller's beer and Polaroid commercials sustained the holiday mood of the game. But Mitchell and Emery -- and the dozens of other candidates in other markets who peddled their arguments between innings -- really should have stood in bed.

There are times when I would be prepared to listen to Emery, the Republican congressman and Senate nominee, pledge to fight against foreign imports. But not when Joaquin Andujar has a no-hitter working in a scoreless game. There are times when Mitchell, the appointed Democratic senator, could convince me that his challenger really is a "down-the-line" supporter of Reaganomics. But not when Lonie Smith has just hit a "down-the-line" double to advance Ozzie Smith to third and set the stage for Keith Hernandez' bases-loaded single.

Time was when politicians respected the World Series, and kept their mouths shut until the championship had been settled.

But that was in the old days, when the season was 154 games, not 162, and there were no intra-league playoffs to push the Series back to within two weeks of Election Day. The rule of wretched excess has afflicted both politics and the sport, and no one is content to stay within his season.

If they were at least dealing with the issues on the minds of the fans, there might be an excuse for their moving in on the games. But they insist on talking about imports and interest rates and other irrelevancies.

Why not a good debate on the legitimacy of artificial surfaces on baseball fields? I happened to have been rooting for the Cardinals in the Series, and to have won a modest sum betting on their success. But if they had won that last game, 1-0, on the three ricochet singles they bounced off the Astroturf in the fourth inning, it would have been a tainted victory.

Baseball was meant to be played on grass and dirt, not on some sort of weird plastic that they shampoo and fluff-dry.

I will cast my vote for any candidate who will promise to ban synthetic surfaces from the ball fields of America and, incidentally, who will find a commissioner of baseball who knows enough to call a game and come in out of the rain.

The last presidential candidate who really focused on the role of baseball in American life was Eugene J. McCarthy -- and we all know how badly that campaign ended. Unless A. Bartlett Giamatti is willing to get out of the Yale presidency and into politics, there is not much hope of having a baseball-oriented campaign by a man who understands that the game should be played on grass in places like Fenway Park, Wrigley Field or County Stadium.

But the horde of candidates who will not help us reform baseball at least could refrain from mucking it up with their commercials.

They really should not invite comparisons with the men on the diamond. The contrast between the pre-packaged clones, who come out of the modern candidate-factories with their three-piece suits, their mod haircuts and their sincere expressions, and the unshaven, uninhibited originals of baseball is cruel to the politicians.

If it's leadership we need in America, we could trade half the Cabinet for Whitey Herzog or Harvey Kuenn, and, speaking of trades, it should not go unnoticed that the man who saved the Cardinals' victory was Bruce Sutter, the relief pitcher the Cubs chose to trade rather than pay two years ago.

This year, the ex-Cub won it. Next year, the Cubs.