A former state delegate from Montgomery County, Mizeur said she was encouraged by supporters to run for the Senate and gave it much thought because of her regard for Mikulski. However, she said she decided not to run for personal reasons.
"Ultimately, I'm just not ready to embark so soon on a grueling statewide campaign," Mizeur said. She said she is not ruling out a return to elective politics in the gubernatorial election year of 2018.
" I am still rebuilding my capacity to give of myself in such a big way again," she said in a Facebook posting.
Mizeur, 42, ran a strong grassroots campaign last year and finished in third -- close behind the second-place Attorney General Douglas F. Gansler -- in the Democratic primary won by Lt. Gov. Anthony G. Brown. Her campaign was distinguished by her strongly liberal positions, including support for the legalization and taxation of marijuana.
Mizeur's decision leaves Van Hollen and U.S. Rep. Donna Edwards as the two declared Democratic candidates to succeed Mikulski. Mizeur said she is not prepared to endorse a candidate in that race or the 8th District contest now.
"I want to see how those races unfold," she said.