Samuel Joseph Wurzelbacher, who briefly became “Joe the Plumber,” the metaphorical American middle-class Everyman, by injecting himself into the 2008 presidential campaign in an impromptu nationally-televised face-off with Barack Obama over taxing small businesses, died on Sunday at his home in Campbellsport, Wis., about 60 miles north of Milwaukee. He was 49.

The cause was complications of pancreatic cancer, his wife, Katie Wurzelbacher, said.

Mr. Obama, then a United States senator from Illinois, was campaigning on Shrewsbury Street, in a working-class neighborhood of Toledo, Ohio, on Sunday, Oct. 12, 2008, when Mr. Wurzelbacher interrupted a football catch with his son in his front yard to mosey over and ask the Democratic nominee about his proposed tax increase for some small businesses.

During a cordial but largely inconclusive five-minute colloquy in front of news cameras, Mr. Wurzelbacher said he was concerned about being subjected to a bigger tax bite just as he was approaching the point where he could finally afford to buy a plumbing business, which he said would generate an income of $250,000 a year.

Three days later, “Joe the Plumber,” as he was popularized by Mr. Obama’s Republican rival, Senator John McCain, was invoked some two dozen times during the final debate of the presidential campaign.

Mr. Wurzelbacher became a folk hero of sorts during the campaign’s final weeks, particularly among McCain supporters and conservative commentators who cottoned to his remarks that Mr. Obama’s share-the-wealth prescriptions for the economy were akin to socialism or even communism and contradicted the American dream. Mr. McCain’s running mate, Gov. Sarah Palin of Alaska, also jumped in, appearing onstage with Mr. Wurzelbacher at rallies.

But by Election Day, his tenure as a burly, bald, iron-jawed John Doe eroded as the public learned that he was not a licensed plumber (he could work in Toledo only for someone with a master’s license or in outlying areas) and owed $1,200 in back taxes.

He flirted with supporting Mr. McCain but later referred to him as “the lesser of two evils” on the ballot and never revealed for whom he had voted that November.

“Let’s still keep that private,” his wife said by phone on Monday.

In 2012, Mr. Wurzelbacher won the Republican nomination to challenge Representative Marcy Kaptur, the Democratic incumbent in Ohio’s 9th Congressional District, but was crushed in the general election, winning only 23 percent of the vote to her 73 percent.

During that campaign, he released a video defending the Second Amendment and blaming gun control as having helped enable the Ottoman Empire to commit genocide against Armenians in the early 20th century and Nazi Germany to carry out the Holocaust, saying gun laws had stripped the victims in both cases of the ability to defend themselves.

Again defending a right to bear arms, he wrote to parents of the victims of a mass shooting in 2014 in Isla Vista, Calif., near the campus of the University of California, Santa Barbara, saying, “As harsh as this sounds — your dead kids don’t trump my Constitutional rights.”

Samuel Joseph Wurzelbacher was born on Dec. 3, 1973, to Frank and Kay (Bloomfield) Wurzelbacher. His mother was a waitress, his father a disabled war veteran.

After high school, he enlisted in the Air Force, where he was trained in plumbing. He was discharged in 1996, and worked as a plumber’s assistant as well as for a telecommunications company.

Capitalizing on his celebrity after the 2008 election, he appeared in TV commercials promoting digital television; published a book, “Joe the Plumber: Fighting for the American Dream” (2009, with Thomas Tabback); and covered the Israeli ground invasion of Gaza in 2009 for PJ Media, a conservative website. In 2014, he went to work in a Jeep plant.

In addition to his wife, who had been Katie Schanen when they married, he is survived by a son, Samuel Jr., from his first marriage, which ended in divorce; and three children from his second marriage, Samantha Jo, Henry and Sarah Jo.

Although Mr. Wurzelbacher ended his encounter with Mr. Obama by shaking hands with him, he didn’t seem satisfied by the candidate’s response to how his tax proposal would affect a small plumbing business.

“If you’re a small business — which you would qualify, first of all — you would get a 50 percent tax credit, so you’d get a cut in taxes for your health care costs,” Mr. Obama explained. And if his business’s revenue were below $250,000, he added, its taxes would not go up.

“It’s not that I want to punish your success; I just want to make sure that everybody who is behind you, that they’ve got a chance at success, too,” Mr. Obama added. “My attitude is that if the economy’s good for folks from the bottom up, it’s gonna be good for everybody.

“If you’ve got a plumbing business, you’re gonna be better off,” he continued. “If you’ve got a whole bunch of customers who can afford to hire you — and right now everybody’s so pinched that business is bad for everybody — and I think when you spread the wealth around, it’s good for everybody.”

Mr. Wurzelbacher was unpersuaded.

“It’s my discretion who I want to give my money to,” he would later say repeatedly. “It’s not for the government to decide that I make a little too much, and so I need to share it with other people. That’s not the American dream.”

Ms. Wurzelbacher insisted on Monday that her husband’s encounter with Mr. Obama in 2008 was completely spontaneous, not staged by Republican operatives or anyone else, and that Mr. Obama’s appearance in the neighborhood had actually been arranged by a neighbor down the block.

“It was completely coincidental,” she said. “It always amazed him that one question thrust him into the national spotlight.”