Bill Cooper spent two decades building what was once a failing thrift into the Minnesota banking power TCF Financial Corp.

Then, just into Cooper’s brief Florida retirement, the brutal downturn that started in 2007 threatened both the company and his own fortune. For Cooper, there was only one way to respond: get back to work.

“I have a real emotional attachment to this company. It’s like one of my children,” Cooper said when he returned to the company in 2008. “I also have a real economic attachment, which may be a stronger attachment.”

Cooper, 73, died Tuesday night at a Twin Cities hospice after being ill for several years with a blood cancer. He remained TCF’s chairman until his death and an animating figure in Minnesota’s business and political communities, and an activist for school choice.

Banking colleagues credited Cooper’s original thinking as a big factor in TCF’s success.

“Bill Cooper was not a me-too banker,” said Craig Dahl, who succeeded Cooper as TCF’s chief executive in 2015.

“That set us apart in the early days, thanks to his innovations,” Dahl said. “He started seven-day-a-week banking, supermarket banking in this market and giving every customer a debit card. He was a leader and a pioneer.”

Cooper was always outspoken and often controversial. His colleagues recalled him as a taskmaster who was by turns stern, witty and kind, with a heart for disadvantaged kids.

He was a rare banker who publicly criticized regulators. In politics, he chaired the Minnesota Republican Party for two years in the late 1990s and took on Democrats and even some GOP moderates.

“He was the most demanding guy as well as the most courageous guy I ever met,” said Greg Pulles, a former TCF general counsel.

Cooper grew up in Detroit and worked as police officer in college. He became an accountant who worked for big banks in Detroit and Ohio before being hired in 1985 to lead the former Twin City Federal Savings and Loan, a near-death thrift that was burdened with $1 billion in nonperforming loans.

The extent of the firm’s challenges became clear when Cooper took the company, renamed TCF, public just a year later. It took years to resolve bad debt and build a profitable business around basic-banking products, such as free checking and debit cards, as federal regulators kept a close eye.

“Bill came up with program that satisfied those guys,” Pulles said of the company’s recovery in the late 1980s. “They left with confidence that he was a banker who knew what he had to do. ... He saved the place.”

TCF spread branches throughout the area and relied heavily on fees to build revenue. Today, the company operates the state’s third-largest bank after the local operations of Wells Fargo & Co. and U.S. Bancorp. TCF Financial has $21 billion in assets, about 90 branches in Minnesota and about 250 others in six other states.

As employees at the company’s corporate office in Plymouth learned of Cooper’s death Wednesday morning, written and video tributes went up on its internal website.

As one of Minnesota’s biggest donors to Republican candidates and causes, Cooper upon becoming state party chairman in 1997 boldly predicted that it would retake the state House majority in the next year’s election. The GOP had held the majority for only two years out of the previous two decades. But in November 1998, Cooper was vindicated when the GOP won the House majority, which it held for the next eight years.

Still, Cooper’s tenure wasn’t all upside. The GOP’s effort to hold onto the governor’s office after Republican Arne Carlson’s two terms fell short, when then-St. Paul Mayor Norm Coleman finished second to independent Gov. Jesse Ventura.

“He had very high standards, very high expectations of both himself and other people, and he lived by them,” Carlson said. “Bill Cooper … truly lived the American dream, and I deeply respect him for that.”

A few years later, while serving as the state GOP’s finance chairman — essentially the party’s chief fundraiser — Cooper formed what he called a Conservative Council to “analyze candidates’ voting records and report on who is a real conservative and who is a ‘Republicrat’ posing as a conservative,” he wrote in 2002.

That earned him a public rebuke from Tim Pawlenty, then the state House majority leader, who later that same year was elected governor even though Cooper backed another Republican in the race.

Cooper continued to donate money to politicians after leaving party service. While Republicans received by far the largest share of his contributions, he occasionally gave money to Democrats — including Sen. Amy Klobuchar. In recent years he was less politically vocal, saying in 2009: “I’m burnt out in politics.”

Vance Opperman, independent lead director at TCF, said one of Cooper’s “greatest legacies” is Friends of Education, a network of charter schools in the region. Cooper started by supporting Ascension grade school, a Catholic school in Minneapolis with a back-to-basics approach that educated mostly low-income minority kids. Cooper and TCF also supported a second group, Student Achievement Minnesota, that authorizes charter schools.

“His work on charter schools was as great an achievement, or even greater, than his success with the bank,” said Rudy Boschwitz, who served on TCF’s board for a decade after leaving the U.S. Senate in 1991.

Cooper first retired from TCF in 2005 and moved to Florida, complaining of Minnesota taxes. He returned in July 2008 as the nation’s housing crisis threw the banking industry into crisis. As one of its largest stockholders, he’d lost millions even though TCF hadn’t made the risky subprime loans to consumers that damaged bigger banking firms.

He gained some national attention as a critic of the government’s bank industry bailout and new regulations. “I certainly don’t need some clown in Washington telling me what to do,” Cooper said in 2009.

In recent years, TCF became embroiled in battles with regulators over fees banks collected on debit card transactions and the fees they charged for overdrafts. And both Cooper and TCF were criticized by shareholders over executive pay, including Cooper’s own seven-figure compensation.

Coming out of the crisis, Cooper developed new lines of business and maintained profits, though TCF’s stock price still trades below its pre-recession level.

While he often groused about Minnesota’s taxes, Cooper also appreciated his opportunity and success in the state.

“I love Minnesota,” he said in 2007. “Minnesota has been good to me.”