Former D.C. Council member Michael Brown in March 2011. (Michael Temchine/The Washington Post)

From a distance, Michael A. Brown was the picture of Washington success: Son of a political legend, member of the D.C. Council, well-dressed lobbyist, owner of a sprawling upper Northwest home.

It became, in recent years, an upscale facade. Tax liens, mortgage troubles and unpaid rent hinted at deep financial difficulties for Brown, who lost a reelection bid last year and whose bills mounted with a lavish lifestyle and lengthy divorce.

Between July and March, Brown was so desperate for funds that he took $55,000 in cash from a company that he thought was seeking business opportunities with the city government, federal authorities alleged Friday. In fact, the business leaders were undercover investigators with the FBI.

On Friday, prosecutors charged Brown, 48, with bribery, alleging he accepted the cash in exchange for a promise to help the business secure contracts with the city and a key government certification.

The charge was presented in a criminal information, a document that can be filed only with a defendant’s consent and that typically indicates a plea deal has been reached.

D.C. corruption scandals: A look at the investigations and where they stand.

Brown told supporters Thursday night that he planned to plead guilty, and his lawyer confirmed the plan Friday. A hearing has been set for Monday at the U.S. District Court in Washington.

“He has accepted full responsibility for his mistakes, cooperated with the authorities and intends to plead guilty,” said attorney Brian M. Heberlig in a statement that also said Brown “made a serious lapse in judgment at a time when he faced severe financial difficulties.”

For Brown, the guilty plea amounts to the most dramatic lapse to date in a public life that has seen many of them.

The son of Ronald H. Brown, the late commerce secretary and Democratic National Committee chairman, the younger Brown grew up in the District’s upper-middle-class “Gold Coast” along 16th Street NW.

He followed his father into politics, pursuing a career in lobbying before choosing, about eight years ago, to seek public office in his home town.

Though benefiting from his father’s good looks, easy charm and political connections, Brown has struggled at times to make his own way in Washington. Twice he ran unsuccessfully for public office — for mayor in 2006 and for Ward 4 council member the next year — before winning an at-large seat in 2008 under unusual circumstances. With longtime incumbent Carol Schwartz ousted in the Republican primary, Brown dropped his Democratic Party affiliation to take advantage of city laws reserving some at-large seats for other parties.

A 1997 guilty plea to a federal campaign finance violation along with business disputes before assuming office hinted at Brown’s troubled relationship with money. His dual salaries as council member and lobbyist — adding up to more than $365,000 in 2010, the most recent year for which disclosures were available — did not alleviate his financial woes.

In 2009, three foreclosure notices were recorded on Brown’s 4,000-square-foot Chevy Chase home — something Brown attributed to a filing error. In 2011, he paid a $14,263 tax bill after The Washington Post reported that he had been delinquent since 2009. Earlier that year, the Internal Revenue Service filed a lien against his home for unpaid taxes dating to 2004.

More recently, he faced expenses relating to his divorce from his wife of 21 years, Tamera A. Brown. The couple separated in 2004, and Tamera Brown filed for divorce in 2011, seeking child support, mortgage payments and home expenses. Meanwhile, Brown was sued three times for late payments on an apartment he rented on 16th Street NW, near where he grew up. The cases were withdrawn.

The divorce is pending, with a trial set for August. The couple’s home has been on the market since April 2012. Originally listed for $1.8 million, the price was recently reduced to $1,665,000.

There was little outward evidence, however, of Brown’s financial turmoil.

Andre Johnson, a public relations consultant who has known Brown for decades and worked on his 2006 mayoral campaign, said he had no inkling Brown was undergoing financial pressures.

“He never gave anyone a reason to believe he was having problems,” Johnson said. “It seemed like he had the means to live the lifestyle he was living. But you never know what people go through in their personal struggles.”

More obvious was the fact that Brown’s political career was becoming a shambles.

As an incumbent with a familiar name and extensive Rolodex, his reelection in 2012 should not have been in doubt. But late last June, about four months before the election, Brown announced that $114,000 had disappeared from his campaign account. He blamed the missing money on a theft by his former treasurer, whose attorney in turn alleged that Brown had knowledge of the disbursements. Roughly two weeks after he made those accusations, Brown embarked on his eight-month course of illegal activity, prosecutors said.

According to the three-page charging document, Brown in that time “corruptly demanded, sought, received, accepted and agreed to receive and accept things of value” from representatives of a business identified as “Company M” that was part of the FBI sting operation.

The charging papers and two people Brown spoke to during phone calls with supporters Thursday evening indicated that “Company M” sought Brown’s assistance in becoming a “certified business enterprise” — a status that gives small, local, woman- or minority-owned contractors an advantage with city contracts. Brown promised “official assistance” to the firm in return for the cash, prosecutors said.

Harold B. Pettigrew Jr., who directed the city department in charge of the certification process at the time, said Brown was one of several D.C. Council members who contacted him seeking assistance for potential contractors. “None of them really asked for special help,” he said.

Bribery of a public official carries a penalty of up to 15 years in prison and a fine of up to $250,000. Under federal sentencing guidelines, Brown faces far less potential punishment. More details of the undercover operation are expected to come out after Brown enters his guilty plea, scheduled Monday before U.S. District Judge Robert L. Wilkins.

What remains unclear is what led prosecutors to undertake the sting operation. Undercover operations involving public officials are not common, according to a law enforcement source who requested anonymity because of the ongoing case.

Justice Department guidelines for undercover FBI operations require investigators to have reason to believe that the target is already involved in criminal activity.

“There has to be a solid basis,” said Mary Patrice Brown, a former chief of the criminal division in the District’s U.S. attorney’s office who is now in private practice.

She said it is not unusual for investigators to examine one matter and then end up filing charges related to another matter entirely.

No criminal charges have been filed with respect to the missing campaign funds, a controversy that contributed to his loss to David Grosso in last November’s election. A spokesman for U.S. Attorney Ronald C. Machen declined to comment on that investigation because it is ongoing.

Brown’s charge has reopened D.C. Council wounds left from the 2012 prosecutions of council member Harry Thomas Jr. (D-Ward 5), who admitted to stealing $353,000 from city-funded youth programs, and Chairman Kwame R. Brown (D), who pleaded guilty to a felony bank fraud charge.

Yvette M. Alexander (D-Ward 7), a friend and political ally of Brown’s, put it bluntly.

“Right now, the residents of the District of Columbia have to be sick of this, they really do, because I’m sick of it,” she said. “It’s ticking me off. Everyone is looking through a side eye now. Everyone.”

Ann E. Marimow and Aaron C. Davis contributed to this report.