GULFPORT, MS - JUNE 22:  U.S. Sen. Thad Cochran (R-MS) looks on during a campaign rally at Gulfport-Biloxi International Airport on June 22, 2014 in Gulfport, Mississippi.  Tea Party-backed Republican candidate for U.S. Senate Chris McDaniel, a Mississippi state senator, is locked in a tight runoff race with incumbent U.S. Sen. Thad Cochran (R-MS) who failed to win the nomination in the primary election.  (Photo by Justin Sullivan/Getty Images)
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(CNN) —  

Former Sen. Thad Cochran, a soft-spoken but powerful Republican who represented Mississippi in Congress for more than four decades, died Thursday at age 81, his longtime spokesman Chris Gallegos said.

“Cochran’s family extends its gratitude for the support shown to the senator by Mississippians over the years,” it said. A cause of death was not immediately disclosed.

Cochran used his influence atop the Appropriations Committee to steer billions to his home state, one of the poorest in the nation, especially after it was ravaged by Hurricane Katrina in 2005.

“As Appropriations Chairman, he wielded great influence with abundant grace,” said a statement from Senate Majority Leader Mitch McConnell, a Republican from Kentucky.

McConnell added: “Thad will be first remembered as a tireless champion of his fellow Mississippians. He took great pride in keeping promises to the people he represented – ensuring veterans’ access to care, improving educational opportunities, and continuing a record of stellar constituent service for every single Mississippian.”

President Donald Trump tweeted praise of Cochran noting that despite illness he returned to the Senate in 2017 to vote on an Affordable Care Act repeal measure that ultimately failed when former Republican Sen. John McCain of Arizona voted against it, stunning the country.

“Very sad to hear the news on the passing of my friend, Senator Thad Cochran. He was a real Senator with incredible values - even flew back to Senate from Mississippi for important Healthcare Vote when he was desperately ill. Thad never let our Country (or me) down!” Trump said.

Cochran, an Eagle Scout and lawyer, also chaired the Agriculture Committee and was considered widely influential on farm issues.

“He was, without question, one of the most impactful senators in agricultural policy in the last hundred years,” said Sen. Roy Blunt, a Republican of Missouri, who also described his former colleague as “a great person to work with and always a gentleman.”

As he was running for a seventh term in 2014, Cochran barely survived a primary challenge from tea party-backed candidate Chris Daniel and only after appealing to Democrats to vote in an open primary.

“Democrats turning out for Cochran is just the tip of the iceberg in an already bizarre race marred by name-calling, mudslinging, allegations of cheating and a break-in at a nursing home where the senator’s bedridden wife lives,” CNN reported at the time.

Cochran’s health declined in the last few years before he left the Senate in 2018 as he was serving his seventh term. He was absent from the Senate for several weeks with a recurring urinary tract infection.

At the time, longtime Senate aides, who observed Cochran regularly, noted privately that the senator seemed to have slowed down mentally in recent years before his retirement, but they acknowledged it was difficult to tell how severely he was affected.

Cochran was the 10th longest-serving senator in history. In 1972, Cochran was elected to Congress and served until 1978, when he was elected into the Senate. He was the first Republican in more than 100 years to win a statewide election in Mississippi.

“I’ve done my best to make decisions in the best interests of our nation, and my beloved state,” Cochran said in his statement when he announced he would leave the Senate. “My top concern has always been my constituents in Mississippi.”

In his farewell address on the Senate floor in March 2018, he was hopeful about his colleagues and the future of his country.

“I leave the Senate confidence that our enduring Constitution guards our country from human errors, empowers our citizens to achieve greatness, and shines as a beacon of freedom and liberty for the world,” he said. “We have engaged in heated arguments. But even in full disagreement, I believe all our motivations begin at the same point: the sincere desire to serve our states and country.”