Brown, who lives in Mitchellville, plans to make the announcement a day after former State's Attorney Glenn F. Ivey said he, too, will run for the seat — setting up what is likely to be one of the state's most closely watched Democratic primaries next year.
Brown, 53, ran an unsuccessful campaign for governor last year, losing to Republican Larry Hogan in a surprising upset. But the Democrat performed well in Prince George's County and has high name recognition after spending millions on television advertising in the Washington media market.
Edwards, the Democrat who has held the seat since 2008, is running to replace retiring Sen. Barbara A. Mikulski. The district includes portions of Prince George's and Anne Arundel counties.
Ivey, 54, of Cheverly, won elections for state's attorney in 2002 and 2006, and has remained close to Democratic power brokers in Prince George's County since then.
"I've been in public service for most of my career and certainly have enjoyed it and have demonstrated success with it," he said Wednesday. "As far as I know, I'll be the only candidate in the field who has ... not only name recognition but also positive name recognition."
Ivey worked for longtime Rep. John Conyers of Michigan, former Sen. Paul S. Sarbanes of Maryland and former Senate Majority Leader Tom Daschle. He is now an attorney at Leftwich & Ludaway in Washington, where he focuses on white-collar criminal defense, congressional investigation and civil litigation.
Brown's name had been floated as a possible candidate for Senate when Mikulski last week announced her retirement, but the idea met with some pushback from state Democrats, who quietly suggested it was too soon for Brown to run statewide after such an upset loss.
Brown, who was born in New York, served five years as an Army helicopter pilot. He completed his active duty in 1989 as a captain and remained in the Army Reserve until last summer. After attending Harvard Law School, where he was a classmate of Barack Obama, he moved to Maryland and took a job with a Washington law firm.
He served as lieutenant governor under Gov. Martin O'Malley from 2007 until January.
Brown's entrance into the race sets up something of a familial rematch: Ivey's wife, former state delegate Jolene Ivey, ran as a lieutenant governor candidate against the Brown ticket in the Democratic gubernatorial primary last year. Brown won the nomination but lost to Hogan in November.
But many of the factors that plagued Brown in the gubernatorial race — the failed launch of the state's health care website, the relatively low turnout in a strong year for the GOP, an electorate that some polls suggested had grown weary of Democratic control in Annapolis — would likely be less important in the 4th Congressional District contest in 2016.