Former U.S. Rep. Martin Olav Sabo, a longtime Minnesota congressman whose quiet Scandinavian demeanor conveyed a sense of civility during increasingly partisan times in Washington, has died at age 78.

Sabo died Sunday morning at Abbott Northwestern Hospital in Minneapolis, according to his daughter, Karin Mantor. She said her father, a longtime smoker who was on oxygen, had been hospitalized for a week because he was having trouble breathing. Doctors discovered Sabo had a mild case of pneumonia, Mantor said, but the cause of death was not immediately known.

Sabo served 28 years in the U.S. House, easily winning each re-election and eventually rising to House Budget Committee chairman. The Minneapolis Democrat announced his retirement in 2006 and was succeeded by fellow Democrat Keith Ellison, the first Muslim elected to the House.

Minnesota politicians praised Sabo, a Norwegian Lutheran, for his understated manner and ability to deliver millions of dollars to the Twin Cities for road and housing projects, including the Hiawatha Avenue light-rail line and the Minneapolis Veterans Medical Center. The Martin Olav Sabo Bridge, a 215-foot-long suspension bridge for bicyclists and pedestrians in Minneapolis, is named in his honor.

Gov. Mark Dayton said Minnesota has important infrastructure projects because of Sabo's senior position on the House Appropriations Committee. The Democratic governor called Sabo "a great political leader and outstanding public servant."

U.S. Sen. Amy Klobuchar, D-Minn., recalled Sabo agreeing to do joint lawn signs with her when she first ran for Hennepin County attorney.

Rep. Martin Olav Sabo, D-Minn., center, flanked by Rep. Mark Kennedy, R-Minn., left, and Rep. Collin Peterson, D-Minn., took part in a Capitol Hill news conference in 2001 calling on Major League Baseball to save the Minnesota Twins from contraction. Stephen J. Boitano | AP 2001

"He was a veteran congressman and I was a political rookie, but he didn't hesitate to help. He saw it as part of his job to help young people get started in politics," Klobuchar said in a statement.

Before being elected to Congress, the North Dakota native served 18 years in the Minnesota Legislature, where he was first elected in 1960 at age 22 and rose to House minority leader, and then speaker.

"Sabo's quiet leadership style and dedication to his district are a true inspiration. He showed us the progress that can be made when Democrats and Republicans work across the aisle for the common good," Minnesota DFL Chairman Ken Martin said in a statement.

In announcing his retirement after a 46-year-old political career, Sabo called putting together the 1993 federal budget as House Budget Committee chairman one of his proudest accomplishments. He also cited the so-called Minnesota Miracle — the 1971 Legislature's groundbreaking overhaul of the state's school funding system — as a major success.

Sabo also took pride in never publicly disparaging another politician. He said Congress had become more polarized during his time there.

"I've always believed the fundamental problem with politics today are people who over-promise and overstate. I've tried to do the opposite," Sabo said. "I've also tried to treat my colleagues with respect. I don't recall ever making a public statement critical of my colleague, whether it's Democrat or Republican."

Funeral arrangements are pending.