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During a closed-door meeting on Capitol Hill Wednesday, liberal firebrand Rep. Alan Grayson angrily confronted Senate Minority Leader Harry Reid over the senator’s decision to back a different candidate in Florida’s Senate race, according to three sources in the room. Reid fired back by expressing his “low opinion” of Grayson.

The outburst prompted a Reid staffer in the room to bring in the senator’s security detail, who stood inside the door during the rest of the meeting as a precaution.

Reid met with members of the Congressional Progressive Caucus, but when Grayson was called on to speak, he repeatedly asked Reid if the senator knew his name.

“Yes, Alan,” Reid replied.

“Say my name,” Grayson insisted more than once.

Grayson then produced a printed-out news article that featured a quote from Reid criticizing Grayson’s ethics issues.

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Asked why he gave the quote, Reid replied, “Because it’s true and I want you to lose.”

Read this story at msnbc.com.

Other members of Congress asked Grayson to step aside, saying this was neither the time nor place for a personal matter.

Rep. Keith Ellison, who was running the meeting as the co-chairman of the Progressive Caucus, told Grayson, “Nobody in the room is supporting what you’re doing right now.”

Eventually, the meeting moved on to Rep. Ruben Gallego, who made a joke before asking a question about DREAMers.

Grayson, who has built anational progressive following in part for his willingness to break with Democratic leadership, is running to fill the Florida Senate seat being vacated by Sen. Marco Rubio. However, Democratic leaders have lined up behind Rep. Patrick Murphy instead of Grayson.

In a statement, Reid spokesperson Kristen Orthman said Grayson embarrassed himself.

“Senator Reid was honored to be invited by the Congressional Progressive Caucus to discuss issues on which he and they can work together. Alan Grayson decided to be disruptive, to the embarrassment of his fellow colleagues,” Orthman said.

“Senator Reid took the opportunity to express his low opinion of Congressman Grayson to his face and remind him that the reason Senator Reid has said that Grayson is under ethics investigation and appears to be running a Cayman Islands hedge fund from his Congressional office in order to line his own pockets is because these things are true, as established by seventy-four pages’ worth of evidence from the Congressional Ethics Committee,” she added in the statement.

Grayson, for his part, responded through a spokesman.

"Calling out the Establishment is never easy, and it's not always polite. I had a rare moment to challenge the lies that Sen. Reid has spread about me, and Sen. Reid made it clear that he's too heavily invested in the Republican sock puppet he's calling a Democratic Senate candidate to consider the truth of the matter," he said. "Sen. Reid ought to learn that ‘I want you to lose’ is no excuse for a gross smear. But the air is cleared."