Representative Jim Hagedorn, a second-term Minnesota Republican who was a staunch ally of former President Donald J. Trump and who joined with other members of his party in seeking to overturn the election of Joseph R. Biden Jr., died on Thursday. He was 59.

His wife, Jennifer Carnahan Hagedorn, the former chair of the Minnesota Republican Party, announced the death on Facebook. She did not specify the cause or say where he died. He had long been public about his three-year struggle with cancer and announced in January that he had tested positive for Covid-19.

Mr. Hagedorn was diagnosed with stage IV kidney cancer in 2019, shortly after he was sworn in as a first-term member of the House of Representatives. He underwent immunotherapy treatment at the Mayo Clinic, and doctors removed the affected kidney in December 2020. He said at the time that 99 percent of the cancer was gone, but he announced in July that it had returned.

Mr. Hagedorn had run for a House seat three times without success, in 2010, 2014 and 2016, when he lost by a hair to the incumbent, the Democrat Tim Walz. In 2018, after Mr. Walz left to run successfully for governor, Mr. Hagedorn narrowly won his seat in a race against the Democrat Dan Feehan.

In a rematch against Mr. Feehan in 2020, Mr. Hagedorn won by a slightly larger margin, despite his health issues, and was raising money in anticipation of a re-election campaign in November.

“He’ll forever be known as a common sense conservative who championed fair tax policy, American energy independence, peace through strength foreign policy and southern Minnesota’s way of life and values,” his campaign said in a statement.

Throughout his short tenure in office, Republicans were in the minority in the House. All the while, Mr. Hagedorn remained a strong conservative, worked on behalf of small businesses and rural entrepreneurs, and stood as an ally of Mr. Trump, who won Mr. Hagedorn’s district in 2016 by 15 percentage points.

“I’ve said repeatedly since 2016 that of course I support Donald Trump,” Mr. Hagedorn told the Minnesota newspaper The Star Tribune in 2019, “because I felt like if he’d lost, we’d have lost the country.”

In December 2020, Mr. Hagedorn was one of 126 Republican members of the House who filed an amicus brief urging the Supreme Court to overturn the election of Mr. Biden as president, a brief based on spurious and disproved allegations of widespread voter fraud. The court rejected the suit, which had sought to throw out the election results in four battleground states.

Just hours after the deadly insurrection at the Capitol on Jan. 6, 2021, by a mob of Trump supporters, Mr. Hagedorn was among 147 Republicans who objected to certifying Mr. Biden’s election.

“There was no stronger conservative in our state than my husband,” his wife wrote in her statement, “and it showed in how he voted, led and fought for our country.”

James Lee Hagedorn was born on Aug. 4, 1962, in Blue Earth, Minn., near the Iowa border. His father, Tom Hagedorn, was a U.S. House member and represented some of the same southern Minnesota territory as his son later did. His mother, Kathleen (Mittlestadt) Hagedorn, was a homemaker.

Jim was raised on the family farm near Truman, Minn., and in McLean, Va., while his father served in Congress, from 1975 to 1983.

He graduated from George Mason University in Virginia with a bachelor’s degree in government and political science in 1993. While a student, he worked as a legislative aide to Representative Arlan Stangeland, another Minnesota Republican. He later worked as a congressional liaison at the Treasury Department and as the congressional affairs officer for the Bureau of Engraving and Printing until 2009.

During the early 2000s, Mr. Hagedorn wrote a blog called “Mr. Conservative,” which has since been deleted. His posts took aim at Native Americans, gay people and women, among others.

In 2005, when President George W. Bush nominated a woman, the White House counsel Harriet Miers, to the Supreme Court (she ultimately withdrew her name), Mr. Hagedorn described her nomination as an effort “to fill the bra of Supreme Court Justice Sandra Day O’Connor.”

The blog posts resurfaced during Mr. Hagedorn’s unsuccessful run for the House in 2014; he told The Star Tribune that they were old and had been satirical in nature. They surfaced again in 2018, when he won the seat chiefly by proclaiming his loyalty to Mr. Trump.

Complete information on his survivors was not available.

The final piece of legislation that Mr. Hagedorn introduced, on Feb. 9, was a resolution to place a national debt clock in the House chamber.

“The American people deserve full transparency about this nation’s fiscal affairs,” he said, “and this resolution will be a strong reminder to lawmakers as they vote on proposals that could put our country further in debt.”