Philip Scott Andrews/The New York Times

Federal regulators are poised to sue Jon S. Corzine over the collapse of MF Global and the brokerage firm’s misuse of customer money during its final days, a blowup that rattled Wall Street and cast a spotlight on Mr. Corzine, the former New Jersey governor who ran the firm until its bankruptcy in 2011.

The Commodity Futures Trading Commission, the federal agency that regulated MF Global, plans to approve the lawsuit as soon as this week, according to law enforcement officials with knowledge of the case. In a rare move against a Wall Street executive, the agency has informed Mr. Corzine’s lawyers that it aims to file the civil case without offering him the opportunity to settle, setting up a legal battle that could drag on for years.

Without directly linking Mr. Corzine to the disappearance of more than $1 billion in customer money, the trading commission will probably blame the chief executive for failing to prevent the breach at a lower rung of the firm, the law enforcement officials said. If found liable, he could face millions of dollars in fines and possibly a ban from trading commodities, jeopardizing his future on Wall Street.

In a statement, a spokesman for Mr. Corzine denounced the trading commission for planning to file what he called an “unprecedented and meritless civil enforcement action.”

The aggressive action would stand in contrast to the government’s investigations so far into the 2008 financial crisis, many of which produced symbolic fines. In the case of Lehman Brothers, which imploded at the height of the crisis, no employee has ever been charged with civil or criminal wrongdoing.

An MF Global case, expected to be filed in federal court, could become something of an experiment for federal regulators under pressure to adopt a harder line against Wall Street. It would also thrust the trading commission — the financial industry’s smallest regulator — onto a bigger stage.

A case would darken the cloud over the legacy of Mr. Corzine, 66, who as a onetime Democratic governor and senator from New Jersey and a former chief of Goldman Sachs has long been a confidant of leaders in Washington and on Wall Street.

But it would also suggest that authorities have all but removed a greater threat: criminal charges. After nearly two years of stitching together evidence, criminal investigators have concluded that porous risk controls at the firm, rather than fraud, allowed the customer money to disappear, according to the law enforcement officials with knowledge of the case.

Still, the spokesman for Mr. Corzine, Steven Goldberg, said that the trading commission’s anticipated lawsuit “is not surprising considering the political pressure to hold someone liable for the failure of MF Global,” the largest Wall Street bankruptcy since the 2008 financial crisis. Lawmakers and even some agency officials, he noted, have publicly condemned the firm.

“If the C.F.T.C. brings this enforcement action, Mr. Corzine would welcome the opportunity to litigate this matter in an impartial venue, free from politically influenced prejudice and unfounded assertions, which have been frequently repeated despite the lack of a factual basis,” Mr. Goldberg said.

The trading commission has not told other top executives that they will be sued, according to lawyers briefed on the case. The regulator appears more likely to take aim at lower-level employees tasked with protecting customer accounts.

The agency faces a lower threshold for proving its charges than criminal authorities do. Prosecutors must prove their case beyond a reasonable doubt, but the agency would only have to show a preponderance of the evidence.

Yet the trading commission is not expected to accuse Mr. Corzine of authorizing the breach of customer money, the officials with knowledge of the case said. Instead, the agency is likely to say that he failed to sufficiently supervise the firm and is subject to so-called control person liability, a legal provision that allows for the punishment of executives for the bad acts of lower-level employees.

As MF Global teetered on the brink of collapse, employees in Chicago transferred customer money to plug holes in the firm’s own accounts, causing a shortfall for clients like hedge funds and farmers whose funds vanished into banks and clearinghouses. The money might have never disappeared if the banks had not pocketed the customers’ money.

“During the difficult final week, Mr. Corzine was never informed, nor was he ever given reason to believe, that customer funds were at risk or were being used improperly,” Mr. Goldberg said. “Justice would not be served if Mr. Corzine were to be blamed for alleged mistakes that were made without his knowledge.”

Some internal e-mails lend support to Mr. Corzine’s defense. An e-mail reviewed by The New York Times indicates that an employee in the firm’s Chicago office, Edith O’Brien, explicitly stated to Mr. Corzine that money was a “house wire,” meaning that it came from the firm’s own accounts, not from customers. Ms. O’Brien, who oversaw the transfer of customer money during the firm’s final week, has been a focus of the investigation since its onset.

For months, she declined to cooperate with authorities without receiving immunity from criminal prosecution. Federal authorities hesitated to grant her request, according to the officials close to the case, but started to reverse course this spring when they invited her to an interview.

For now, Ms. O’Brien is likely to receive immunity from criminal prosecution, but she or her direct bosses could still face a civil action from the trading commission, the officials said. Ms. O’Brien has not been accused of any wrongdoing.

A spokesman for the F.B.I. in Manhattan declined to comment. The trading commission also declined to comment.

MF Global filed for bankruptcy on Halloween 2011. Months later, the trading commission’s investigation escalated even as criminal scrutiny petered out. Early this year, people involved in the case said, the regulator deposed Mr. Corzine.

The investigation presented a test for the agency’s enforcement division, which has adopted a more aggressive stance under David Meister, a former federal prosecutor who joined the agency in 2010.

Ultimately, Mr. Meister’s team warned Mr. Corzine’s lawyers, Andrew J. Levander and Benjamin E. Rosenberg at Dechert, that it planned to recommend an enforcement action against him. The division, according to people with knowledge of the case, planned to accuse the executive of a “failure to exercise adequate supervision,” stemming from a breakdown in the firm’s internal controls.

Mr. Goldberg said the allegation would be “nothing more than another example of Monday morning quarterbacking,” a defense first raised when MF Global’s bankruptcy trustee sued Mr. Corzine and his aides in April.

According to the lawsuit, an October 2010 internal report warned Mr. Corzine about certain “high risk” areas stemming from the lack of controls.

While such warning signs could support the trading commission’s case, it plans to level a second charge that could be more difficult to prove. In claiming “control person liability,” the agency must show that Mr. Corzine had control over Ms. O’Brien or any other employee who may have transferred customer money. It also must prove that he either “did not act in good faith” or knowingly “induced” an employee to break the law. While Mr. Corzine is thought to have received e-mails with estimates of customer money, authorities appear to lack a smoking gun.

The agency has successfully relied on the statutes that cover failure to supervise and control person liability in previous cases, but it has never used them in such a prominent action.

Mr. Goldberg said that regulators “regularly reviewed MF Global and had never found fault with its systems and procedures for maintaining customer funds.”

Since the collapse of the firm, Mr. Corzine has kept a low public profile. Lately, however, he has ventured out a bit. He recently visited Central America for a humanitarian project involving children, for example. And last week, he was seen at an old haunt in Lower Manhattan, Esquires of Wall Street, an 81-year-old barbershop that Mr. Corzine has frequented since his days at Goldman.