Manning, a former United States Army intelligence analyst, was convicted by court-martial in 2013 of leaking hundreds of thousands of classified documents - including information about the war efforts in Iraq and Afghanistan, State Department cables and information about prisoners in Guantanamo Bay - to WikiLeaks. Cardin, a senator for the last decade who spent twenty years in the House of Representatives before that, is considered a fairly liberal Democrat, but a race against Manning would highlight the stylistic differences between a youthful progressive movement and the aging generation of party leaders.
When another Twitter user criticized Manning's diatribe on police last week and said "have fun never voting again", she responded that she was registered to vote despite her criminal record: "state of maryland doesnt disenfranchise".
Manning made waves in a different way when she posed in a red one-piece bathing suit for Vogue's September issue, eliciting both supportive and critical comments. She will run as a Democrat.
The primary will be held on June 26, 2018, ahead of the November 6 general election that Democrats are eying as a chance to retake Congress and restrain president Donald Trump.
President Trump has been critical of Manning, once referring to her as an "ungrateful traitor". US officials said the material placed the lives of USA soldiers and Afghan informants at risk, but Manning said she had a duty to inform the public about how the USA was conducting its wars. She was placed in solitary confinement after twice trying to kill herself. Ben Cardin, D-Md., speaks during a Senate Foreign Relations Committee hearing on.