Below is my column in USA Today on the real danger of the Stormy Daniels case.  The danger in the campaign finance allegation is the fact of the investigation not necessarily the charge itself.  The fact that there is an ongoing investigation presents a more straightforward basis for prosecutors to allege obstruction than in the Russian investigation.

Here is the column:

Despite the well-earned criticism of Rudy Giuliani for his first interview as President Trump’s new counsel, the fact is that Giuliani was given a daunting task.

The legal team had clearly concluded that (with the raid on Trump’s personal counsel, Michael Cohen) it could no longer factually or legally defend the president’s prior blanket denial of an affair or knowledge of the agreement with porn star Stormy Daniels. Giuliani failed in the pivot rather spectacularly and might have done the impossible in making Cohen look competent in comparison. Giuliani later corrected his statements, and Trump went public to rebuke him to “get his facts straight.” Trump added the general advice to “learn before you speak. It’s a lot easier.”

The danger, however, is far greater than a lawyer learning about a case live on television like some legal reality show. The problem for Trump is that the Daniels controversy could supply the obstruction case that has long evaded special counsel Robert Mueller.

In a Sunday interview on ABC’s This Week, Giuliani continued to search for terra firma. At one point, Giuliani was reduced to insisting that while he could no longer assert facts as counsel, “I can prove it’s rumor. But I can’t prove it’s fact. Yet. Maybe we will.”

Somewhere in there is a good defense lost in bad delivery.

Giuliani was continuing to try to advance a line of defense called the “irrespective test” under the Federal Election Commission (FEC) rules that allow for a finding that an expenditure is personal if it’s “any commitment, obligation or expense of a person that would exist irrespective of the candidate’s election campaign.”

It is a valid defense, and it is particularly familiar to White House counsel Donald McGahn, who was an FEC commissioner.

But the legal legacy of the Trump administration is a litany of self-inflicted wounds. Trump insisted recently that you cannot obstruct a case if there is no underlying crime. In truth, that is no easy feat, but Trump is making an impressive effort.

The problem has never been his case (or cases). He has a strong defense in his choice to fire FBI Director James Comey, for example. A president can have multiple reasons for firing a political appointee, and Comey was viewed by former attorneys general and career prosecutors as warranting termination at the start of the administration. Virtually all of the claims of obstruction in the Comey matter have come from Trump’s own interventions and comments to Cabinet members, Russian diplomats, staff and news media.

Despite Trump’s best efforts, the evidence falls substantially short of a credible obstruction case. The case is made all the more difficult by the president’s use of discretionary constitutional authority to retain or remove political appointees.

The Daniels case, on the other hand, could present a much easier case for obstruction or related crimes. There are no complicating constitutional powers or political judgments. The New York prosecutors are investigating the payments and have conducted a raid that, in part, sought information related to payments to Daniels as well as similar payments to Playboy model Karen McDougal.

Efforts to withhold evidence, encourage false testimony, or influence witnesses could present credible foundation for criminal charges ranging from witness tampering, obstruction to subornation.

The Trump team appeared to finally recognize that Cohen had put the president in the worst possible position with his payment of hush money and incriminating past statements. Giuliani then took a bad position and made it far, far worse. He tried to reframe the payment of the $130,000 from a gift to a loan from Cohen, thereby tripping a series of new potential criminal and ethical violations without (as he seemed to assume) getting the president out of the campaign-finance threat.

The greatest danger of the campaign-finance allegations, however, is not the charge itself. These violations are rarely charged criminally and, as shown in the failed prosecution of former Democratic presidential candidate John Edwards, difficult to prove.

Rather, the greatest danger is the response to the investigation into campaign-finance violations or fraud. Again, all the prosecutors need is a criminal investigation to lay the foundation for more serious crimes such as obstruction.

Perhaps for that reason, Trump went out the morning after Giulliani’s first disastrous interview to deny the former New York mayor’s assertions. Then, in an even more embarrassing turn, Giuliani himself insisted that he was “not describing my understanding of the president’s knowledge, but instead, my understanding of these matters.”

However, the “matter” at issue is the president’s knowledge. If the president was involved in sending out a false public account by both his private counsel and White House staff, it could be treated as a potential criminal matter. Likewise, any evidence that Cohen was warned or in any way protected by government officials before the raids could prove incriminating.

Even more worrisome are accounts that Trump continued to call Cohen even though he was warned about the danger of interception and possible cooperation. According to NBC News, Trump made at least one call after his own Justice Department raided Cohen’s office and Cohen was rumored to have recorded conversations with his clients. The recklessness of such a call is impossible to overstate. If prosecutors believe that there is a campaign-finance violation or fraud, such contacts could easily lay the foundation for more serious criminal allegations for Trump.

Trump has always portrayed himself as a vicious “counterpuncher.” However, the federal code has a crime designed specifically for counterpunching in the midst of a criminal investigation. That is how a porn star could succeed where a special counsel fails. Indeed, if Trump is not careful, that is how a porn star could take down a president.

Jonathan Turley, a member of USA TODAY’s Board of Contributors, is the Shapiro Professor of Public Interest Law at George Washington University, where he teaches constitutional and tort law. Follow him on Twitter: @JonathanTurley.