But Sen. Jon Tester, the DSCC chairman, made clear that this is not a state he believes can afford blue-on-blue warfare, and at the same time, suggested Murphy would make a "great senator."
In a year where the party has chosen a handful of veteran candidates as it standard-bearers, Murphy is a standout. "He's young, he's a fantastic fundraiser, he's a moderate who has won a tough Republican district who won't have a problem garnering statewide appeal," said one national Democratic strategist.
Asked about a possible primary contest with Grayson, Murphy's camp sent a statement: "Rep. Murphy is receiving tremendous support from Democrats from across the state. He's been a strong advocate for a woman's right to choose and marriage equality in the country, while working to lift up Florida's middle class families. He's looking forward to continuing his conversations about these important issues."
For his part, Grayson called the rumors of widespread Murphy support "annoying."
"Why do you think Patrick would even stay in the race? Based on the way the major Florida groups line up, don't you think that even Patrick would reach the obvious conclusion?" Grayson said. "If it's true that the party doesn't want a contested primary, what makes you think I'd be the one who drops out?"
Some of Grayson's biggest supporters, liberal groups such as Democracy for America and the Progressive Change Campaign Committee, also are upset about the party's treatment of Murphy. "Floridians would not take kindly to the DSCC meddling in a Democratic primary for Senate, especially on behalf of someone who has left the door open to cutting Social Security benefits," PCCC co-founder Adam Green said in a statement.
"We've supported Alan Grayson through all of his congressional races. Our members really like him," said Democracy for America's Neil Sroka. "He speaks to a real desire within the base of the Democratic Party to have outspoken leaders against the powerful and wealthy. "¦ We just want to make sure that there's a free and open debate of ideas without the national party getting in and trying to decide who should and shouldn't run at all."
Democrats' best hope for avoiding a primary may well be Rubio himself. Grayson said he is eyeing what the incumbent does in 2016—run for reelection or give up the seat to run for president—as he considers his own next steps: "I'm not anxious to jump into this without having a better sense of whether Rubio is serious when he says he's not going to run for reelection [if he runs for president], and I think that dynamic is still unfolding."
His national fundraising base and personal wealth means there's no incentive to jump in early, and he wants to be certain of the path of victory, Grayson says.
"It's something I'm not going to take lightly, I like what I do and I'm good at it," Grayson said. "If you lose you're no good to anybody, I discovered that already "¦ I don't see any other way to do this kind of work at the level that I do other than in the House or the Senate or the White House, or maybe as Pope."