As we told you, over the weekend, Republican Sen. Mitt Romney accused former Democratic congresswoman and presidential hopeful Tulsi Gabbard of “parroting false Russian propaganda” over her comments about U.S.-funded biolabs in Ukraine and said that “her treasonous lies may well cost lives.”

Romney has worked very, very hard to be viewed as a relatively reasonable guy, but there’s no doubt he made a mistake when he suggested that Gabbard is guilty of treason. There are legitimate criticisms to be made, but the T-word only serves to convey the message that Romney is just throwing words at the wall in the hopes that one of them will stick. It’s not an ideal strategy, and Mitt’s ultimately hurting himself more than he is Gabbard.

This morning, Gabbard called on Romney to put up or shut up and apologize.

Regardless of whether or not you agree with Tulsi Gabbard on any particular issue, it’s hard to argue that she’s not pretty fearless when it comes to defending herself. She doesn’t back down.

But maybe she can still take some comfort in knowing that Glenn Greenwald is ready to back her up if she ever decides she needs it. Last night, Greenwald got to work taking Mitt Romney to task, and he’s still at it today:

Needless to say, Greenwald’s not feeling very generous when it comes to indulging Romney’s criticisms of Gabbard:

That’s not an unfair question.

Mitt Romney is free to disagree with Tulsi Gabbard. And he’s free to call her out and criticize her. But if he’s going to pull the “Treason” card, he’d better have the receipts. Otherwise, he’s just sliming her to slime her.

And as a victim of smear campaigns himself, Romney should be more thoughtful than that.