Paul, previously 'the most interesting man in politics,' is now just scenery in the 2016 campaign. How long can he stay in the race?

Last Monday, former Congressman and three-time presidential candidate Ron Paul wrote to express his support for the Iran nuclear deal. The negotiation, he said, was "one of the two most important achievements of an otherwise pretty dismal Obama presidency" and, further, it proved "that sometimes taking a principled position means facing down overwhelming opposition from all sides and not backing down."

Awkwardly, that opposition includes Rand Paul, his son, who not coincidentally is finding himself struggling in the polls and in the money race as he campaigns for the Republican presidential nomination.

According to an NBC News/Marist poll released Sunday, Paul commands just 4 percent support in New Hampshire–a loss of 10 percentage points since February.

Paul's second-quarter financial haul was $7 million, which places him behind every Republican who has disclosed their earnings except for Carly Fiorina, who you may not have even heard of, Rick Perry, who is under indictment in Texas and barely qualifies for the first debate, Rick Santorum, who doesn't qualify, Bobby Jindal, who had just six days to fundraise, and Mike Huckabee, whose campaign platform seems to be uncomfortable Holocaust references. 

Paul's super PAC, America's Liberty PAC, raised just $3.1 million. In comparison, Jeb Bush's super PAC raised $103 million.

Noting Paul's collapse, FiveThirtyEight asked, "What's Wrong With Rand Paul's Campaign?" The answer, writer Harry Enten concluded, was that Paul had faded from the headlines and, simultaneously, his favorability among Republicans had declined.

But that's more of a symptom than the cause of the cancer on Paul's candidacy. The root of the decay is this: As Rand Paul has campaigned, it has become increasingly evident that he is not the candidate his supporters were promised he would be–a more electable version of his father. And the candidate he did turn out to be is not interesting or authentic enough to stand out from the 20,000 other Republicans seeking the nomination. Paul, previously "the most interesting man in politics," is now just scenery.