Minneapolis — After Minnesotans finish voting for president next week, they may sense a little deja vu in their choice for the United States Senate. The incumbent, Rudy Boschwitz, is an affable Republican who supports President Reagan's economic programs. Not surprisingly, challenger Joan Growe campaigns on many of the same themes as Minnesota's own Walter Mondale.
These links were reinforced Sunday night by both Senate candidates in their only televised debate of the campaign.
Like Reagan, Senator Boschwitz came off looking like ''a warm, fuzzy figure, '' says Steven Schier, assistant professor of political science at Carleton College. On the other hand, says Mr. Schier, Ms. Growe appeared ''a bit school-marmish,'' attacking Senator Boschwitz incessantly but rhetorically. ''I rather saw too much of Mondale in Joan Growe.''
The debate itself may not swing too many voters, Schier adds. Boschwitz holds a 10-point lead, according to the most recent poll by the Minneapolis Star and Tribune. But that is Growe's best showing so far. By some estimates she will close the gap even more.
''As a matter of fact, we're a little ahead of schedule,'' says Steve Novak, Ms. Growe's campaign manager. ''I expect it will be a very close election.''
''We've said for a long time that the race will get tight,'' says Scott Cottington, campaign manager for Senator Boschwitz. ''Joan is no slouch.''
Boschwitz, stumping recently in the cafeteria of a downtown Minneapolis bank, fielded bank employees' questions with ease.
Budget deficits? Cut spending if possible - otherwise, raise taxes, he says. Budget reform? Give the President line-item veto authority over the budget - but carefully. Members of Congress ''aren't dumb. They'll put it all on one line,'' says the senator.
The audience laughs. The down-home appeal of Boschwitz, clad in blazer and his trademark flannel shirt, seems to work.
The same day, Minnesota Secretary of State Growe presses her offensive. Addressing separate teachers' conventions in Minneapolis and St. Paul, she charges ''a pattern of deception by Senator Boschwitz to cover up his conflict of interest.''
Later, in an interview in her Minneapolis apartment, she renews the attack: ''What you're looking at is someone who is voting for special interests rather than the people of Minnesota.'' She cites three specific areas: Boschwitz's refusal to make public his income tax returns, his refusal to go along with her pledge not to tinker with social security, and his support for a controversial product-liability bill.
Homing in on the product-liability question in a recent speech, Ms. Growe charged that the senator's cosponsorship of such a bill was a conflict of interest. The reason: his brother, Franz Boschwitz, owns a wood-products manufacturing company that has been a defendant in several suits alleging formaldehyde poisoning.
The bill would likely make it more difficult for Minnesota consumers to collect damages in such cases.
Upon learning of the possible conflict of interest, Boschwitz immediately withdrew as a cosponsor, his aides say. He continues to support the bill in amended form, which would replace a hodgepodge of state laws with a national one , says lawyer and campaign adviser Jann Olsten, who adds: ''It's a gross oversimplification to say it makes it more difficult to sue.''
Boschwitz aides are also upset about Ms. Growe's pressing the matter of releasing income tax returns. Says press secretary Tom Mason, ''He's not going to do it to satisfy the whim of some political wizard in Ohio'' - a reference to one of Ms. Growe's consultants, who was recently quoted as saying that he could bring Boschwitz down.
Ms. Growe brushes off such criticism, saying the issue is not her consultant but Boschwitz's record.
Her aides concede they have no evidence of any tax irregularities on the senator's part, but say they want to see if he benefited inordinately from the 1981 Reagan administration tax cuts. Boschwitz, a millionaire plywood retailer who says he has suffered severe financial losses in recent years, supported the tax cuts.
Whether such tactics by Ms. Growe can make a difference by election day remains to be seen. ''My seat-of-the-pants judgment is that she can't close it up,'' says William Hathaway, professor of sociological and behavioral science at the General College of the University of Minnesota who is active in Republican politics.
For Ms. Growe to win, she must carry traditional Democratic strongholds such as Minneapolis-St. Paul and the Iron Range, while garnering 42 percent of the rural vote, says campaign manager Novak.
In the early 1970s, that would have been relatively easy in Democratic Minnesota. But over the past decade a particularly heated debate over abortion has torn apart the Democratic-Farmer-Labor organization built by Hubert Humphrey.
''It's civil war,'' said one state political expert, who asked not to be named. The schism over abortion, which is not a vocal issue in the campaign, may nevertheless give pro-life Boschwitz the election. Ms. Growe's pro-choice stance may cause a healthy chunk of pro-life Democrats to vote Republican. Pro-choice Republicans are more likely to stay with the party, this observer says.
Another unknown is what coattail effect a Mondale victory in his home state would have on the Senate race. But observers and the polls suggest a lot of ticket-splitting.
In the closing days of the campaign, a great many voters apparently remain undecided.
The Star and Tribune poll, carried out with the assistance of the Gallup Organization, shows that 58 percent of those surveyed expressed less than strong support for either candidate, or were undecided.