The outline of the story is more than vaguely familiar. On one side there is a folksy Republican incumbent wrapped in a protective coating of money, incumbency and a nice-guy image. On the other side is a Democratic challenger who's trying to find an issue sharp enough to poke through.

But this isn't Reagan versus Mondale. It's the Senate race between Rudy Boschwitz and Joan Growe.

The parallels with the presidential campaign have not been lost on the people in Fritz Mondale's home state. Republican Sen. Rudy Boschwitz is something of an anomaly in politically moderate, issue-oriented Minnesota. The conservative senator, a millionaire businessman with a penchant for plaid shirts and root-beer-flavored milk, came into the public eye originally on television ads for his plywood company and zany billboards. Among the more memorable billboard messages was one suggesting: "Unite St. Paul and Minneapolis, Drain the Mississippi."

He won his seat in 1978 essentially because Minnesotans were mad at the way former Gov. Wendell Anderson had gotten himself appointed to Mondale's Senate seat. But the Democratic Farmer-Labor candidate is also something of an anomaly.

Joan Growe is the only woman to run for the Senate in Minnesota since the 1920s. The 49-year-old former teacher and secretary of state for the past 10 years decided in 1983 that Boschwitz was "vulnerable." Not because of his plaid shirts; because of his record. He had become, as Ted Kennedy called him. "Rubber Stamp Rudy" for Reagan.

"Vulnerable" is, however, a relative term in politics. In this heralded "year of the woman," there have been 10 females running for the Senate -- six Democrats and four Republicans. But there's only one female incumbent, Nancy Kassebaum, and only one female front-runner, Nancy Kassebaum. Most of the others are running in what are described in classic understatements as "tough races." As one woman at Democratic headquarters in Washington says ruefully, "Let's face it, in most cases if it's a real shot, then the people at the head of the line to run are men."

The race here was regarded as at least remotely winnable, and Growe only got to the head of the line after winning the party's nomination in a grueling convention and then winning the primary with 76 percent of the vote.

In August, Growe was trailing the genial Boschwitz in the poll by 21 points. But last week, the Minnesota Poll put her within striking distance.

This is not bad for a candidate who didn't get a single ad on TV until after Labor Day and who has been outspent by more than $4 million. Polls also show that Minnesota voters agree with Growe on some important issues -- she is pro-freeze and pro-ERA; he is against -- but they "like" Rudy.

Growe, a hard-working, intelligent, but not charismatic campaigner, decided that she couldn't out-nice-guy Boschwitz. Instead, she has gone after him for refusing to take a no- cut pledge on Social Security, for supporting a controversial product-liability bill and for not releasing his tax returns.

The tax question has been more popular with the people than the press. Boschwitz did release tax "summaries" last August that showed he had paid only 15 percent in 1982, the year of the first Reagan tax cut and of his own business reversals. He refuses to release any more data, claiming "privacy."

But this time Boschwitz has needed more than his plaid shirt to maintain credibility. He has put his accountant into one TV commercial) and his colleague, Sen. David Durenberger (R-Minn.), in another. Durenberger pronounced dourly in a full-page newspaper ad: "Mrs. Growe, you've gone too far."

Growe responds to this with an amused nod. "People used to say I wasn't tough enough," she remembers. "Now when I get tough, they say I'm being mean." At least they haven't accused her of being bitchy.

There is, however, a gender issue in this campaign. The Minnesota Poll showed that if women alone were voting, Growe would be ahead by 3 percent. If men were the only voters, Boschwitz would lead by 22 percent.

But with less than two weeks to go, the gender gap is probably less important than the funding gap or, for that matter, the national ticket gap. Joan Growe's chance to close in, to become "the woman" in the fading "year of the woman," may finally depend on how well Mondale does in this home state. Copyright (c) 1984, The Boston Globe Newspaper Company