Adult-film actress Stephanie Clifford, also known as Stormy Daniels, poses for pictures at the end of her striptease show in Gossip Gentleman club in Long Island, New York, February 23, 2018. Eduardo Munoz | Reuters

Porn star Stormy Daniels' alleged affair with President Donald Trump could yet become a sticking point for special counsel Robert Mueller's ongoing probe of the Trump campaign and White House, experts say. The special counsel is specifically tasked with investigating potential collusion between the Kremlin and the Trump campaign, as well as "any matters that arose or may arise directly from the investigation." Yet several white-collar crime experts told CNBC that Daniels' lawsuit, filed against Trump on March 6 over a deal barring her from discussing an alleged affair, raises questions and opportunities for the Mueller probe. Read more: Stormy Daniels tells '60 Minutes' she feared for her safety when she signed Trump hush agreement That's because of the special circumstances surrounding a payment made to Daniels as part of the deal — and Trump's relationship to the person who made that payment, his longtime personal lawyer Michael Cohen. Daniels' lawyer, Michael Avenatti, declined to answer when CNBC asked whether he has been contacted by the office of the special counsel. "I'm not at liberty to answer that question one way or the other," Avenatti said. Mueller's office declined to comment.

The Cohen connection

Cohen said in February that he made a $130,000 payment to Daniels in October 2016, just weeks before the election that would catapult Trump to the White House. Cohen later said the money came from a home equity line of credit. Daniels, whose legal name is Stephanie Clifford, has said the money was in exchange for her signing a non-disclosure deal facilitated by Cohen through a company he set up shortly beforehand. Daniels gave details of the alleged affair to In Touch magazine in a 2011 interview that wasn't published until earlier this year. Although the relationship between Trump and Daniels allegedly occurred between 2006 and 2007 — shortly after Trump's wife, Melania, gave birth to Trump's youngest son, Barron — the hush-money deal wasn't signed until a few weeks before the 2016 presidential election.

The timing of the payment has raised the question of whether Cohen and the Trump campaign violated campaign finance laws in an effort to prevent Daniels going public with her story just before voters started casting ballots. The amount of money that Cohen gave Daniels was well in excess of the contribution maximum that an individual could make to a campaign. And the expenditure was not disclosed by the Trump campaign. "I think that is something to care about," New York City criminal defense lawyer Gerald Lefcourt said when CNBC asked why Mueller could be eyeing the Daniels deal. "It's a close associate of the president involved in the campaign," Lefcourt said. "If the president knows about it, he's involved in the [potential] campaign violation as well." He added: "Why would [Mueller] not want to know about it? It might not be a major violation, but he'd certainly want to know it." Cohen, in a February statement to The New York Times, denied that Trump campaign or the president's company had anything to do with the payment. "Neither the Trump Organization nor the Trump campaign was a party to the transaction with Ms. Clifford, and neither reimbursed me for the payment, either directly or indirectly," Cohen wrote. "The payment to Ms. Clifford was lawful, and was not a campaign contribution or a campaign expenditure by anyone." Cohen's lawyer did not immediately respond to CNBC's request for comment for this article. Trump lawyer Ty Cobb declined to comment.

The scale of the Mueller probe

Lefcourt said that even if the Daniels situation is not directly tied to the original focus of Mueller's probe — Russian interference in the presidential election — "It's part of a piece." Representatives for Trump have denied he had an affair with Daniels. If the affair did happen, Trump and Cohen's denials could be used by Mueller to cast into doubt the reliability of their claims about other areas of his investigation. "This information would go generally to both of their credibilities and, more specifically, to both of their potential modus operandi for trying to control information that might be adverse to the president's interests," said Stephen Braga, a white-collar criminal defense professor at the University of Virginia's law school. Braga also said Mueller might be able to use the potential threat of prosecuting Cohen for actions related to Daniels as leverage to get him to cooperate in the ongoing probe of the Trump campaign. He noted that Mueller has used this "standard prosecutorial tactic" to win guilty pleas from other targets in his probe, including former Trump campaign advisor George Papadopoulos, former national security advisor Michael Flynn and former campaign official Rick Gates.

'A potential cooperator'

The infamous dossier from an ex-British spy, which surfaced after the 2016 election, alleges that Cohen secretly met with Russian government officials in Prague in August 2016. The dossier, which was partially funded by the Democratic National Committee, made salacious claims about Trump's connections to Russia, many of which remain unverified. Cohen has adamantly denied the dossier's allegations and has specifically said that he has never been to Prague. In January, he sued Buzzfeed for publishing the dossier. Mimi Rocah, a former federal prosecutor in New York and MSNBC contributor, said that Mueller may see Cohen as a means to gain more information about Trump. "It may be that this doesn't connect directly to Russia, but rather that Mueller sees Cohen as a potential cooperator," Rocah said. Mueller's team, she said, would be unlikely to look into the lawsuit between Trump and Daniels unless they suspected a "significant link to the broader investigation." After the hush deal was first reported, Cohen in January issued a statement in Daniels' name denying the affair, as well as "rumors that I have received hush money from Donald Trump." But earlier this month, Daniels sued Trump in a California state court, asking that the non-disclosure agreement be voided because Trump never signed it. In her suit, Daniels said that she had an intimate relationship with the president. Trump and Cohen now want the case to be transferred to a federal court in Los Angeles. and have warned that Daniels could be subject to at least $20 million for violations of the non-disclosure pact.

WATCH: 'Stormy' prepared to return Cohen payment