Who Let Marco Rubio’s Slimy Pal Into the GOP Debate?

David Rivera is bad for Sen. Marco Rubio’s presidential ambitions—but the ethically challenged former congressman can’t seem to stay away.

On Wednesday, Rivera was spotted at the Milwaukee Republican presidential debate, according to Politico’s Mike Allen. The Tampa Bay Times’ Alex Leary heard the same and tweeted about it. (The Daily Beast confirmed independently that Rivera was spotted.)

“Will it rattle Rubio to see Rivera there?” Allen wrote. Apparently not, as Rubio went on to give a debate performance widely praised by pundits and backed by polling respondents.

Now, not everyone can gain admission into these debates. The tickets tend to be handed out by sponsors, so—in theory—it should be easy to figure out who gave out individual tickets. Unless your guest is David Rivera.

Only a few groups had access to tickets, according to RNC spokesman Sean Spicer: the Republican National Committee, the Wisconsin Republican Party, hosts Fox Business Network and The Wall Street Journal, and the various presidential campaigns.

The Republican National Committee did not give Rivera a ticket. Neither did The Wall Street Journal, nor the Fox Business Network. The Wisconsin Republican Party only gave tickets to elected officials and party supporters, and Rivera has no known ties to the Wisconsin GOP.

So that leaves the Rubio campaign—or Rubio himself—as the only other plausible source of the ticket.

“If he was there, he didn’t get [a ticket] from us,” Rubio spokesman Alex Conant said. “I don’t know anything about his whereabouts.”

So who invited Rivera, who was once one of Marco Rubio’s closest friends?

At this point—it’s a mystery (aka someone is lying).

Rivera has been persistently haunting Rubio’s presidential campaign.

Rivera, who attended the Cleveland Republican debate in August, brings an aura of impropriety with him.

This year a Florida panel recommended that Rivera be given a $58,000 fine for improperly billing the Florida government for expenses while a state lawmaker.

Meanwhile, Rivera has also been under investigation as the alleged mastermind of a campaign finance scheme. While Rivera has been identified as a co-conspirator in the scheme, he has not been charged and has maintained his innocence.

“That’s the problem with David. He’s never been able to control his compulsions. And the problem for Marco is he can’t bring himself to definitely and permanently shake off David. There’s a lot of shared history there,” a longtime Florida political operative told The Daily Beast. “It’s almost pathological, though. [Rivera] has to know his presence there will be noticed and hurt his friend. But he just can’t stay away.”

The history between the two pols goes back to their political infancies: Rubio and Rivera co-owned a house together, from when they were young lawmakers in Tallahassee; and when Rubio first ran for local office, Rivera kicked in a hundred bucks, one of Rubio’s first donations. Rivera was, as Manuel Roig-Franzia put it in The Rise of Marco Rubio, one of his “uber-confidants.”

But Rubio has moved onward and upward: their joint home was sold this year, and while the senator’s star has continued to ascend, Rivera lost his congressional seat in 2012, after one term.

Rivera did not respond to multiple requests for comment.