Pediatric neurosurgeon Ben Carson finally announced the formation of an exploratory committee for a White House run on Tuesday, doing exactly what everyone has been expecting him to do for months.

In a nearly four-minute video, Carson lays out the rationale for his candidacy.

If I run for president, it will be because I know what it's like to grow up in a tough neighborhood and feel marginalized. If I run it will be because I know first-hand that quality education is the ladder to climb out of poverty and dependence. If I run, it will be because I know that the very survival of our great country depends on strong leadership to address our real concerns about security, about jobs, about America's standing in the world. If I run, it will be because it is not acceptable for us to be ignored and dismissed by Washington politicians we entrusted to lead this country.

As a speech on paper, this isn't so bad. The repetition of the "If I run for president" refrain provides for a nice rhythm and echo; it's a common rhetorical device for preachers especially. But Carson, who likes to throw rhetorical red meat when he can, has always been rather weak when it comes to actually delivering the goods. The most recent example came Wednesday morning on CNN as he made the case against gay marriage.  Typical social conservative fare, right. But even as he argued that gayness is a choice, he delivered a fairly controversial and downright odd statement in that  detached tone that is his style.

Asked by New Day anchor Chris Cuomo if gayness is a choice, Carson said:

"Absolutely. Because a lot of people who go into prison go into prison straight, and when they come out, they're gay. So, did something happen while they were in there? Ask yourself that question.”

It's a fiery statement, without the fire. (He also notably said in that same interview that he has learned from his mistakes that he needs to tone down some of his rhetoric. Lesson not learned).

There's always been a gap between what he says and how he says it. Carson, who tends to speak softly and prefers short sentences, often sounds like a man explaining complex topics to a small child. His pacing is deliberate and precise. He sounds exactly like the surgeon he is.

But that type of bedside manner isn't great for a political campaign where a candidate must channel and rouse emotions. I've written before about how Carson has inspired a cult-like following among conservatives. His books sell out in Christian bookstores, and before his Fox News contract was canceled, he was a regular on that network. At last week's CPAC, he effectively tied for third place with Sen. Ted Cruz (R-Tex.).

But in the fundraising race, Carson isn't likely to come close to the top-tier candidates. His viability as a long-shot candidate will be based on his ability to catch fire, earn free media and have memorable showings on a debate stage. Mike Huckabee and Herman Cain, both ministers, were able to do that in the last cycles, because they spoke forcefully and in quotable soundbites. They were both good salesmen -- 9-9-9! -- and Carson is not, at least not yet.

If he wants to keep competing with the likes of Cruz, he will have to ratchet up his political presentation, or risk being drowned out by more forceful and inspiring contenders.