Carl R. Wagner. (Family photo)

Carl R. Wagner, a Democratic Party strategist, organizer and adviser for 40 years who counseled and worked for President Bill Clinton and Sens. Edward M. Kennedy and George S. McGovern, as well as a corps of other Democratic officeholders and office seekers, died June 23 at his home in Washington. He was 72.

A spokeswoman for the D.C. Medical Examiner’s office said determination of the cause of death is pending further investigation. His daughter, Alex Wagner, a co-host of “CBS This Morning: Saturday,” said he had heart and lung ailments.

Mr. Wagner co-chaired Clinton’s victorious 1992 presidential campaign and was a longtime friend of the former president. They met in 1972, when both were working on the Democratic presidential campaign of McGovern, the South Dakota senator who lost in a landslide to incumbent President Richard M. Nixon.

Mr. Wagner was helping run the McGovern campaign in sections of the Midwest. Clinton, fresh from Yale Law School, was directing McGovern’s efforts in the Southwest.

“For so many years, Carl was there with clear-eyed analysis of a tough problem, honest advice in a tough spot, and unflinching support in a tough fight,” Clinton said in a statement. “He played a big role in helping us think through my decision not to run for President in 1988. . . . [He] was one of the finest organizers and one of the best political minds of our generation.”

Mr. Wagner was serving as director of political activities for the American Federation of State, County and Municipal Employees (AFSCME) when Kennedy, the Massachusetts senator, hired him in 1978, two years before Kennedy attempted to wrest the presidency from incumbent Jimmy Carter, a fellow Democrat.

He was Kennedy’s “field general and a palpably brilliant strategist and tactician,” David M. Axelrod, a top political strategist in Barack Obama’s presidential campaigns, said in an email to The Washington Post.

To Les Francis, deputy chief of staff in the Carter White House and a former executive director of the Democratic National Committee, Mr. Wagner was a “hot type” political tactician, “very intense, high energy . . . could push, demand, got things done.”

Mr. Wagner tended to side with the underdog and was “not one to play it safe,” said political columnist and commentator Mark Shields, describing him as someone who “played hardball . . . with a devilish grin.”

In negotiations over whether Kennedy should address the 1980 Democratic National Convention, Shields said Mr. Wagner once suggested to the Carter camp that 5,000 Kennedy partisans could be armed with handheld clickers to drown out pro-Carter speeches if Kennedy were not allowed to speak.

After working for Kennedy, Mr. Wagner launched and managed his own consultancy, continuing to specialize in Democratic Party politics, but also branching out into other issues, including environmental causes.

Over the years, he advised, managed or promoted the political ventures of Sen. Gary Hart of Colorado; Ronald H. Brown, the Democratic National Committee chairman and secretary of commerce under Clinton; and Michael S. Dukakis, the Massachusetts governor who lost the 1988 presidential election to George H.W. Bush.

In 2008, Mr. Wagner supported then-Sen. Barack Obama of Illinois for the Democratic presidential nomination. He directed get-out-the-vote efforts in local and state contests around the country.

Carl Robert Wagner was born on Jan. 14, 1945, in Lansing, Iowa, a small town on the banks of the Mississippi River. His father was a rural letter carrier. He graduated in 1967 from Loras College in Dubuque, Iowa, with a degree in political science and did postgraduate study in politics at the University of Iowa.

Afterward, he worked in Madison, Wis., as an economics specialist in the office of Gov. Patrick Lucey before coming to Washington in the mid-1970s as a political operative for AFSCME.

His marriage to the former Swe Thant ended in divorce. Survivors include their daughter, of New York City.

In 1988, when Clinton was governor of Arkansas, Mr. Wagner was summoned to Little Rock along with other Clinton loyalists for what many thought would be Clinton’s announcement of a presidential candidacy.

“What finally decided the question for me,” Clinton wrote in his autobiography, “My Life,” “was the one part of my life politics couldn’t reach, Chelsea. Carl Wagner, who was also the father of an only daughter, told me I’d have to reconcile myself to being away from Chelsea for most of the next 16 months. . . . Chelsea asked me where we were going for summer vacation. When I said I might not be able to take one if I ran for president, Chelsea replied, ‘Then Mom and I will go without you.’ That did it.

“I went into the dining room of the Governor’s Mansion, where my friends were eating lunch, [and] told them I wasn’t running.”