On October 9, Ben Carson appeared at the National Press Club to promote his new book. His campaign manager, Barry Bennett, told The Daily Beast that Carson’s publishing company set up the event and paid for his transportation to D.C. to speak there.

And just like that, Carson may have violated campaign finance law.

The Republican presidential candidate made headlines last week when ABC News reported that he would suspend his campaign for a tour promoting his new book, A More Perfect Union: What We The People Can Do To Reclaim Our Constitutional Liberties.

Carson’s team took issue with the story, saying his presidential campaign is still very much underway even though he’s making room in his schedule to sell books.

But here’s where it gets complicated.

Carson’s publishing company Sentinel—an imprint of Penguin publishing—is paying for the tour, according to Bennett. And that puts the former neurosurgeon in a tight spot.

Campaign law bars corporations from donating to presidential candidates—whether those donations are checks or in-kind contributions of goods or services. “Campaigns may not accept contributions made from the general treasury funds of corporations, labor organizations or national banks,” reads the FEC’s guide for candidates. (PDF)

That’s why it gets dicey (though not unheard of) when presidential candidates go on book tours; if the hotel stays, restaurant meals, and publicity associated with a book tour are paid for by the publishing company, candidates can get in trouble if they hold campaign events while traveling on that company’s dime.

According to Larry Noble, senior counsel for the Campaign Legal Center, Carson may have already broken that rule.

He said that the October 9 stop at the Press Club looked suspiciously campaign-related. The event was billed it as “NPC Luncheon with Dr. Ben Carson, Author and Presidential Candidate.” More troublesome is the fact that Carson used the appearance to explicitly tout his presidential ambitions.

“[U]nder a Carson administration, if another country attacks us with a cyber attack, they’re going to get hit so hard, it’s going to take them a long time to recover,” he said, according to a transcript of the speech (PDF) he gave there.

After the candidate’s remarks, National Press Club President John Hughes questioned Carson more about what he would do if he gets elected. Carson said he would work with Turkey to establish a no-fly zone over Syria and that he would call a joint session of Congress to tell them to “recognize that the people are at the pinnacle, and that we work for them, and they don’t work for us.”

All of that sounds way more like presidential politicking than book-selling.

“Even though he never says ‘Vote for me as president,’ he’s clearly discussing his candidacy. What he’s supposed to say in that situation is, ‘I‘m really not here to discuss my campaign for president; I’m here to to discuss my book,’” Noble said.

That, of course, is not what Carson said.

Noble added that if another campaign filed a complaint with the FEC regarding Carson’s comments at the Press Club, the commission would likely take that complaint seriously.

“They’d at least need to take a look at it,” he said.

Carson is not under investigation by the FEC but formal complaints can be filed by any person who spots a potential violation. The FEC doesn’t comment on the activity of candidates and has noted in the past that there is always a possibility that matters related to the campaign could come before the commission.

Bennett said he doesn’t think Carson has broken any FEC rules.

“The book publisher has attorneys and we have attorneys,” he said. “It was all vetted.”

A publicity contact for Sentinel has not yet returned a request for comment. We also left a voicemail for Premiere Collectibles, which is billed as promoting his tour, and didn’t get a response by press time.

Carson’s Press Club comments aren’t the only part of his book tour to worry campaign finance law watchdogs. Bennett confirmed to The Daily Beast that from October 4 to October 11, the publisher paid for Carson’s transportation and lodging because he was promoting his book. During this time, the candidate made the rounds on cable TV, discussing current events and his presidential campaign.

“My view is that multiple appearances by a candidate on talk shows to discuss politics amounts to campaign activity and, consequently, that the campaign should have paid some of the transportation and lodging expenses,” emailed Paul Ryan, a spokesperson for the Campaign Legal Center.

Ryan added that similar situations have divided the FEC.

“At any rate, the commission deadlocked so there’s no formal guidance from the commission on this point of law,” he said.

That means Carson stepped into a legal gray area every time he did interviews with political reporters during the week of October 4. Two days later he appeared on Fox and Friends to discuss his campaign.

“I don’t want to be the establishment candidate,” he said. “What has the establishment really gotten us?”

He added that he wouldn’t have met with the families of victims of the Umpqua shooting if he were president.

“I would have so many things on my agenda that I would go to the next one,” he said.

He also appeared on The View on October 6, The Kelly File later that day, and on Hannity on October 7.

This week Carson will juggle fundraising events and book tour stops in Texas, Oklahoma, Missouri, Kansas, Iowa, and Nebraska. On some days, like October 18, campaign events are wedged in between book tour stops. Next Sunday, Carson will promote his book in the Woodlands, Texas, at 2:30 p.m., hustle to a forum at a Baptist church in Plano at 5:25 p.m.—which is a campaign event—and get to San Antonio by 8 p.m. for another book stop. In an effort to avoid FEC violations, the campaign says staffers will only show up at the Plano pit stop.

“FEC rules and regulations call for the separation of campaign and non-campaign finances,” said Ying Ma, deputy communications director for the Carson campaign. “We’re trying to do our best to abide by all requirements. Campaign staff will be at campaign events. That’s what campaign staff do.”