The last time an elected U.S. senator from Minnesota resigned, DFLers botched the resulting appointment so badly that they were swept out of power in the state for years.

It became known as the 1978 "Minnesota Massacre," when DFLers lost both U.S. Senate seats, the governor's office and dozens of seats in the Legislature.

"It was probably the worst defeat the DFL ever suffered, certainly in modern political times, in Minnesota," said Roger Moe, who was a DFL state senator at the time.

Other factors helped topple Minnesota DFLers in that election, but underpinning it all was voter backlash against the Senate appointment.

The series of events began when Walter Mondale was elected vice president in 1976. Mondale was a U.S. senator at the time, so he resigned his seat in late December 1976, a few weeks before being sworn in to his new post. That handed the DFL governor, Wendell Anderson, a political plum — the chance to appoint a replacement.

The immensely popular Anderson was fresh off a smashing re-election victory in 1974, when he buried his Republican opponent by 33 percentage points and won all 87 counties.

"I think he saw his avenue to follow in the footsteps of Humphrey and Mondale, and maybe bigger things," Moe said.

In a monumental miscalculation, Anderson essentially appointed himself to the vacant Senate seat.

He resigned as governor so that his lieutenant governor, Rudy Perpich, who automatically succeeded him as governor, could appoint him to the Senate. Anderson's hubris angered voters, and they struck back at the first chance they got, the 1978 election.

Anderson lost badly to Republican Rudy Boschwitz, who founded Plywood Minnesota, a home improvement retailer.

The other Senate seat also was on the ballot in a special election to complete the remaining term of Hubert Humphrey, who had died earlier that year. Republican David Durenberger won that election.

Rounding out the trifecta of statewide defeats for DFLers, Perpich lost the governor's office to Republican Al Quie.

It didn't end there. DFLers lost many seats in the state House, too. "We probably would've lost [state] Senate seats, too," Moe said. "Thank God we weren't up."

Moe said he doesn't discount the role Anderson's self-appointment played in the DFLers' defeat, but pointed out other factors. It was a midterm election and President Jimmy Carter's unpopularity signaled trouble for Democrats. On top of that, interest rates were in the double digits.

It took years for DFLers to reclaim all three statewide offices. Perpich succeeded in winning the governor's office back in 1982, but the Senate seat that Anderson lost didn't return to DFL hands for 12 years, when Paul Wellstone upset Boschwitz in 1990.

And the Durenberger seat stayed Republican even longer — until the 2000 election. The DFLer who won back that seat was Mark Dayton — now the governor who would get to make a Senate appointment should Sen. Al Franken resign.

Dennis J. McGrath • 612-673-4293