Jerry Springer, a Democratic candidate for governor, has launched the high-risk political ad campaign of the year here. It features him talking about his liaison with a Kentucky prostitute.

"Some nine years ago, I spent time with a woman I shouldn't have. I paid her with a check," the former Cincinnati mayor says in a commercial. "I wish I hadn't done that. The truth is I wish no one would even know."

Then Springer, his boyish face occupying almost the entire TV screen, tries to turn the liaison from a political liability into a plus. "Ohio is in a world of hurt and the next governor is going to have to take some heavy risk and face some hard truths," he says. "I'm prepared to do that. This commercial should be proof. I'm not afraid of the truth, even if it hurts."

No one here is quite sure if the commercial is the act of a political genius or fool. "Ohio is a pretty strait-laced place," says one leading Democrat. "We still have a lot of Waltons living here. This issue is a grenade without a pin."

Springer's decision to run the ad at all is a revealing statement on Ohio politics at a time when the state is reeling under a severe recession and hard-fought primaries are under way in both parties to succeed Republican Gov. James A. Rhodes, who has dominated state politics for two decades.

Springer, 38, isn't your typical midwestern politician. He is a British-born Jewish kid with a shaggy mop of long blond hair. He grew up in New York City, reads The New Republic and brags about his love for the Yankees instead of a good Ohio team like the Reds or the Indians.

Unknown in most of Ohio a few months ago, Springer has become the most intriguing figure in a Democratic gubernatorial race that was supposed to be dominated by two heavyweights, three-term state Attorney General William J. Brown and former lieutenant governor and Carter Peace Corps director Dick Celeste.

Springer, according to several polls, moved briefly into second place behind Celeste with his massive television ad campaign, an unconventional approach to politics and a healthy dose of humor.

He lightheartedly proposed, for example, building a dome over the state (to keep it warm in the winter) and blowing up bridges between Ohio and Kentucky (to keep industry from moving South). "If I'm governor, you'll get up every morning and say, gee, we've got a great governor," he tells audiences.

Springer's campaign, however, has faltered in recent weeks. Brown, a colorless candidate with a good record as an administrator, began to move up after he ran a series of "comparison ads" that claimed Celeste and Springer favored increased taxes and opposed the death penalty.

With the June 8 primary rapidly approaching, Celeste and Springer claim the ads oversimplify the positions of all three candidates. They also charge Brown's campaign with using dirty behind-the-scene tactics. Brown, Celeste told one news conference, was "appealing to the dark side of human nature with lies and distortions" about his opponents.

He said Brown forces had distributed, in unmarked envelopes, a federal report critical of his tenure as director of the Peace Corps, and had begun a whispering campaign against Springer.

Brown denies any involvement in dirty campaign tactics. But a question asked by his pollster, Patrick Caddell, in one poll gave credibility to the charges. Caddell's question read:

"As you may know, in 1974 Jerry Springer, who had gotten married six months earlier, was arrested on a morals charge with three women in a motel room. He also used a bad check to pay for the women's services and subsequently resigned as mayor of Cincinnati. Does this make you much more likely, somewhat more likely, much less likely or somewhat less likely to support Springer for governor?" Springer had never tried to hide the fact that he resigned from the Cincinnati City Council in 1974 after a liaison with a prostitute in a Fort Mitchell, Ky., motel. In fact, press packets distributed at the beginning of his campaign mentioned the incident.

The problem with the Caddell question was that almost every assertion in it was flat wrong. Springer had never been arrested; he'd been involved with one, not three women; he hadn't paid with a bad check, and he hadn't been mayor at the time of the incident.

The Akron Beacon Journal editorially denounced "the shabby performance" by Caddell and Brown as unfitting behavior "from an Ohio attorney general and a political consultant with a national reputation . . . . It was, in short, sleazy politics unbecoming to Ohio."

Brown, questioned about the editorial, said: "I have to agree. It was a mistake on Pat's part." (Caddell could not be reached for comment yesterday, but told Ohio reporters last week that he would accept responsibility for inaccurate information in the question.)

Brown is running as the moderate "manager" in a race against two liberals. "What's wrong with having a governor who doesn't talk about dreams and vision all the time? Sometimes those dreams get very expensive," he says.

Brown enters the final two weeks of the race with one of the state's best political names (he says 38 Browns ran for state office in 1978) and an ample television ad budget. He says Caddell's polls show him leading Celeste, who narrowly lost to Rhodes four years ago, in what has again become a two-man race. "It's mine to lose right now," he adds.

Ironically, his commericals appear to be aiding one of the two leading Republican candidates for governor, Rep. Clarence J. (Bud) Brown (R-Ohio). According to a poll conducted for the state GOP last week, Brown has moved even with Seth Taft, the patrician grandson of President William Howard Taft.

The poll distressed Taft, a former Cuyahoga County (Cleveland) commissioner, who had been leading in the race. "People have heard a lot about Brown, but I don't think they know which one is which," he says.

The Republican race has been a rather dull, gentlemanly affair, completely overshadowed by the Democratic one and by Springer's ad.

Springer admits it is a big gamble. "But you have to remember I'm not running for God. I'm running for governor," he said on the way to an rally in Akron late last week. "What's wrong with the public knowing I'm a human being with warts?"