Democratic Rep. Donna Edwards of Maryland intends to join the race to replace retiring Sen. Barbara Mikulski, hoping to become the first African-American elected to the Senate from her state, according to officials familiar with her plans. Edwards would become the second member of the state’s House delegation to announce her intentions to run for the Senate. Democratic Rep. Chris Van Hollen joined the race last week. No Republican has yet stepped forward to run for a seat in a Democratic state. …