Former D.C. Councilman Michael Brown, whose engaging style and roots in one of Washington's most powerful political families propelled him to the highest levels of municipal government, will plead guilty to a federal bribery charge in the aftermath of an FBI sting operation, a federal law enforcement source said late Thursday.

Brown, 48, will likely be charged on Friday through a criminal information, a type of court filing that indicates the existence of a plea agreement. He did not respond to repeated requests for comment.

A spokesman for U.S. Attorney Ronald Machen Jr., whose office will prosecute the case, declined to comment, but several federal law enforcement officials said that authorities planned to announce a public corruption case on Friday.

It will not be Brown's first skirmish with federal authorities. In 1997, he pleaded guilty to a violation of campaign finance laws.

That conviction, along with a string of driving offenses, personal financial troubles and an alleged six-figure theft from his campaign war chest, helped drive Brown from office in November, when David Grosso easily defeated him.

But Brown, who complained that unfair treatment from the news media was mostly responsible for curbing his re-election prospects, soon opted to enter an April 23 special election for a different council seat. Although he enjoyed widespread name recognition, he abruptly abandoned his campaign weeks before the citywide vote.

At the time, he attributed his exit to "very important personal and family matters that require my immediate attention."

But he didn't disappear from public life entirely, and he offered occasional feedback on Twitter to officeholders and journalists.

He also surfaced at the John A. Wilson Building on April 29 and told a Washington Examiner reporter he was there for "a few meetings."

Brown, the son of a former Cabinet secretary and chairman of the Democratic National Committee, endured a series of electoral failures before winning his council seat in 2008 as a self-styled "independent Democrat." He ultimately ascended to chairman pro tempore of the council, the legislative body's No. 2 post.

A quixotic bid in 2006 for mayor ended before the first votes were counted after he recognized that he had only tepid support. A 2007 run for a council seat also floundered.

Word of Brown's newest legal troubles came on the first anniversary of the resignation of former D.C. Council Chairman Kwame Brown, who quit after prosecutors charged him with bank fraud.