Rep. John Conyers (D-Mich.) will have a challenger in his Democratic primary.
"He's not capable anymore of providing the energetic leadership that is demanded," Sheffield said. "We need aggressive, vibrant leadership in this region."
Conyers, first elected in 1964, is the ranking member on the House Judiciary Committee and second most senior congressman in the House. He has yet to say for sure whether he plans to run for reelection.
This isn't the first time Conyers has faced a primary challenge. He took 55 percent of the vote in 2012 against three primary opponents after his district was significantly altered in redistricting, taking it into Detroit's suburbs.
Sheffield also has some cachet in Detroit — his father was a powerful union member and his daughter is on Detroit's city council.