Sen. Marco Rubio just gave Republican Mitt Romney 8,000 reasons to not pick him as a vice presidential running mate.

Rubio's 2010 Senate campaign was fined $8,000 by the Federal Elections Commission, according to a just-released report that said it received "prohibited, excessive and other impermissible contributions totaling $210,173.09."

By itself, the fine is a pittance for a campaign that raised about $21 million. The errors appear to be relatively small and largely clerical.

Still, it’s sloppy. It’s also a surprise. And it feeds into a broader narrative that Rubio is risky.

Romney’s campaign isn’t the type that suffers sloppiness, surprise or risk. Meantime, the New York-Washington media establishment seems eager to portray the 40-year-old Rubio as unprepared to be a heartbeat away from the White House.

“He is not ready to be on a national ticket in 2012,” former Pensacola Republican Congressman Joe Scarborough said on his Morning Joe program on MSNBC. “He’s not ready to be in the Oval Office. He’s not ready to be vice president of the United States.”

Others, including Alberto Gonzales, White House counsel and attorney general under former President George W. Bush, believe he would be a poor VP pick.

Scarborough made his comments the day before Friday’s disclosure of Rubio’s fine.

To be sure, Rubio is still beloved by tea party activists and conservative leaders, including former Florida Gov. Jeb Bush.

In some respects, Rubio’s problem is a hazard of the campaign business. In 2008, the FEC fined Joe Biden’s brief presidential campaign $218,000. The FEC recently found potential problems with $2 million in contributions to President Barack Obama’s 2008 campaign.

Still, this isn’t Rubio’s first bookkeeping problem.

In 2008, The Miami Herald discovered he failed to properly disclose a generous home loan from a politically connected bank. About the same time, he appeared to ring up some personal expenses on a Republican Party of Florida credit card that was established for political purposes. The Herald and the Tampa Bay Times then discovered Rubio double-billed taxpayers and the RPOF card $3,000 for flights, the costs for which he then reimbursed the state.

Then, late last year, a Rubio critic alerted the press to the fact that the senator’s official website incorrectly said his parents fled Fidel Castro’s Cuba. They actually had fled dictator Fulgencio Batista’s Cuba.

The Herald/Times first reported the story, and was followed the next day by a Washington Post reporter who is writing an unauthorized Rubio biography. That story, though, incorrectly suggested Rubio had personally repeated the falsehood on multiple occasions. Rubio is writing a rival autobiography.

Just last week, in a follow-up, the Post reporter (by way of the Politico website) unearthed a story about the Cuban-immigration struggles of Rubio’s maternal grandfather — whom U.S. authorities ordered deported in 1962 — and tried to compare it to the plight of modern-day immigrants from Mexico.

The piece about Rubio’s grandfather came just as Rubio is winning accolades for a scaled-back DREAM Act immigration proposal to help children of undocumented immigrants. Another Washington Post report noted that the Obama White House appears worried about handing Rubio a win over immigration — a central talking point for Democrats this year.

Opponents are quick to draw attention to every misstep by Rubio.

When Rubio misplaced the final page of a well-regarded foreign-policy speech at the Brookings Institution on Wednesday, liberal commentators happily noted that Rubio should invest in a Teleprompter, which he has criticized Obama for using.

Rubio refuses to talk about the so-called “veepstakes” these days, and has said he probably won’t be offered the job. If he is, it probably will be because polling will show Romney needs him to prevail in must-win Florida, where Hispanic voters are key.

Paperwork problems aside, Romney and Rubio don’t seem to be a natural fit.

Romney is cold. Rubio is hot. Romney is campaigning as the businessman. Rubio is essentially a career politician.

The Rubio-surprise factor also mattered at one point to some of Romney’s current campaign staffers, some of whom worked briefly for then-Gov. Charlie Crist in his bruising Senate race against Rubio in 2010.

On Valentine’s Day two years ago, the campaign sent out a mock Valentine’s candy sampler that listed 10 made-up sweets dinging Rubio for everything from his “Coconut Carbon Tax” to his “Hazelnut Hypo- crisy.”

“Marco Rubio is like a box of chocolates,” the sampler said. “You never know what you’re gonna get.”

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