Leaders of a divided Minnesota Democrat-Farmer-Labor Party led by Vice President Mondale labored yesterday to shape a "unity" campaign to elect their convention-endorsed senatorial candidates - Sen. Wendell Anderson and Rep. Donald Fraser.

But despite get together exhortations in the memory of the late Hubert H. Humphrey by Mondale yesterday and on Friday by Sen. Muriel Humphrey, divisions on abortion and conservation continue to fester in the ranks. Fraser is the target of anti-abortion opponents. Anderson has aroused environmentalists because of his opposition to new restrictions - which Fraser supports - on motorboats and snowmobiles in a huge Minnesota wilderness area.

Anderson is seeking his first, full six-year term, Fraser the remaining four years of the late Humphrey's seat that his widow, Muriel, holds by appointment until after the November election.

Yesterday boos were mixed with cheers and applause when Mondale praised Fraser as the member of Congress enjoying "the highest reputation for integrity, intelligence and courage."

This happened again moments later when Mondale called for the reelection of Rep. Bruce Vento (D-Minn.), coauthor of the Burton-Vento Northern Minnesota wilderness bill that Fraser inspired. Many of the boss apparently arose from about 500 recreational vehicle partisans from northern Minnesota who were sitting in the gallery after a short demonstration outside the St. Paul Civic Center, site of the convention.

Meanwhile, Rep. James Oberstar (D-Minn.), a strong "pro-life" (anti-abortion) candidate and the chief foe of the Burton-Vento bill for restrictions on use of the million-acre Boundary Waters Canoe Area, told reporters he would not campaign for Fraser in a primary contest mounted by businessman Bob Short although Oberstar said he wouldn't campaign for Short either.

Short, a Minneapolis millionaire hotel and truckline operator who once owned the Washington Senators baseball club, skipped the convention but said in a recent interview he planned a vigorous contest. He takes anti-abortion and anti-Burton-Vento bill positions and has accused Fraser of being more interested in foreign affairs than in Minnesota.

Friday night, Anderson, a former governor whose arranged self-appointment to the Senate when Mondale became vice president has backfired in terms of his popularity, won endorsement with only 23 votes to spare over the 60 percent required. It took Fraser three ballots to pass the 60 percent mark and he got 62.2 percent on the third. Some of the balloting made it clear that supporters of Fraser were not necessarily supporters of Anderson and vice versa.

Fraser was not really seriously threatened but his opponent, state Sen. Douglas Johnson, claimed yesterday he could have won if he had started sooner. Johnson entered the contest nine days ago. Johnson said he will not support Fraser.

Fraser is a favorite of pro-abortion groups and the party's liberal wing. Anderson's strength lies generally with party moderates. Although Anderson disappointed "pro-life" delegates on his side by refusing to take a position at this time on whether there should be an anti-abortion constitutional amendment, he can presumably continue to rely on "pro-life" support.