Hillary Rodham Clinton wants to crack down on bad behavior by Wall Street by imposing a new fee on large financial institutions and vowing that individual bankers who violate the law will be "prosecuted and imprisoned."

A new proposal released by her campaign would impose a new, graduated "risk fee" on financial companies with more than $50 billion in assets. The fee would increase as companies hold greater amounts of debt, with the goal of discouraging them from taking on excessive risk.

Clinton's campaign estimates that banks and other institutions would pay an annual charge of "multiple billions of dollars," according to a summary provided by the campaign.

Her proposals came just days before the first Democratic presidential debate with her primary rivals. Liberal Democrats have spent months calling on Clinton to take a more aggressive approach to regulating Wall Street. In recent weeks, Vermont Sen. Bernie Sanders has gained ground against her in early primary states with a populist economic message that vows to take on the "billionaires."

Clinton's close ties to Wall Street and the centrist economic policies of the administration of her husband, former President Bill Clinton, make some in her party skeptical of her populist credentials. Both Clintons have earned millions in speaking fees, including some from Wall Street banks, and daughter Chelsea and her husband have worked at hedge funds.

About a dozen of Clinton's top campaign bundlers -- donors who have raised at least $100,000 for her presidential bid -- work in finance and investing. In July, a day after proposing higher capital gains taxes on short-term investors, Clinton raised at least $450,000 Tuesday night at the Chicago home of Raj Fernando, a longtime donor. His firm, Chopper Trading, specializes in high-frequency transactions and was recently purchased by Chicago-based competitor DRW.

In the first major economic speech of her presidential campaign, last July in New York City, Clinton expressed outrage at accounts of money laundering and currency manipulation involving several major financial firms. She said few rogue traders had faced consequences for malfeasance, a subtle swipe at the Obama administration, which took no action against the individual financial titans who pursued risky fiscal practices.

"This is wrong, and on my watch it will change," she said.

Under her new plan, individual investors, financial managers and traders would face the possibility of tougher criminal penalties. They also would be banned from future employment in the financial industry and could find their compensation penalized as part of a government settlement.

Along with a greater emphasis on punishing individual bad actors, she will also impose a new tax on high-frequency trading, her campaign said. The fee would target trading strategies that involve significant numbers of order cancellations, a practice her campaign says makes markets "less stable and less fair."

Her plan would extend the statute of limitations on major financial fraud cases to allow prosecutors more time to develop a case. She would also increase federal funding for financial regulators including the Securities and Exchange Commission, Consumer Financial Protection Bureau and Commodity Futures Trading Commission, and raise the maximum fines those agencies can levy.

She also proposes limiting the use of pacts, known as deferred prosecution agreements, where the Justice Department agrees not to press criminal charges if a settlement is reached.

Her plan may not go far enough for elements of her party's base, who would like to see the revival of a Depression-era law banning financial institutions from combining their commercial banking operations with riskier investment banking. Two of her rivals, Sanders and former Maryland Gov. Martin O'Malley, say they'd like to see the law, called Glass-Steagall, restored. It was repealed during the administration of Clinton's husband.

Speaking in Iowa this week, Clinton said she isn't focused on reinstating the law.

"The big banks are not the only thing we have to worry about," Clinton said Tuesday in Davenport. "I've studied this real closely, and what I am proposing is we go after the risk, and if they are too big to manage, that is a risk and they should not continue"