"Senator Mikulski has done an outstanding job representing Maryland in the U.S. Senate for nearly 30 years," O'Malley said in a statement. "I am hopeful and confident that very capable public servants with a desire to serve in the Senate will step up as candidates for this important office. I will not be one of them."
O’Malley is seriously considering a presidential bid and the decision not to run for Mikulski's seat furthers speculation about his 2016 aspirations, despite the fact that his candidacy would undoubtedly be an uphill battle against the presumed front-runner Hillary Clinton.
The former secretary of state faced harsh scrutiny after a New York Times report alleged that she only used a personal email account during her tenure at the State Department. The move may have run afoul of federal record-keeping protocols, though Clinton's team maintain the practice was done aboveboard and in line with the rules.
Even prior to the news about her emails, O’Malley had already begun to take on Clinton’s legacy. In a speech this past weekend, he criticized the politics of “triangulation” — the term Obama and other Clinton critics used to criticize the Clintons’ political centrism. Late last year, he went farther to the left than Clinton on a top progressive issue, calling for the prosecution of those involved in the government’s torture program during the Bush years.
Mikulski, 78, announced Monday that she would retire after five terms in the Senate and a decade in the House; she is the longest serving woman in Congress. Her seat is considered safe for Democrats. In the last presidential election, Obama earned 62% of the vote in Maryland.