In the long lead-up to the 2016 presidential campaign, I repeatedly wrote in this space, said on TV and tweeted that Marco Rubio and Jeb Bush wouldn't both run for the nation's highest office. That conclusion was based on the idea, explained to me by many Republicans seemingly in the know, that the duo were too close personally to ever go against one another in any sort of election.

That conclusion, as you undoubtedly know by now, was wrong. Rubio formally announced his candidacy on Monday and Bush, while not officially in the race, is absolutely 100 percent running.

When I screw something up, I like to try and figure out why. It's a service (I hope) to readers and, selfishly, it helps me try not to make the same mistake again. So, I reached out to virtually every Republican consultant I knew with Florida ties in search of answers to two questions: 1) Was the idea that Rubio and Bush wouldn't run against one another ever right and 2) If it was, what changed?

"Hell if I know," said Ana Navarro, a Bush supporter and Florida Republican strategist. "There's no point to psychoanalyzing what could have been, should have been, may have been. We're at the bridge now and have to get to the other side."

I ran into that sense of uncertainty about what (if anything) was at the heart of the mistaken impression about the closeness of the Bush-Rubio relationship. "This one is a hard one, honestly," said one Republican operative who works extensively in the state. "No one knows the solid truth of it other than the governor and Marco."

One Rubio ally, however, had a clear view on what happened. The closeness of Bush and Rubio was "typically overstated by the press," said the source, adding: "Marco got elected to the legislature on his own.  In the Senate race against [Charlie] Crist, Jeb was not particularly impactful, despite reports to the contrary.  Jeb’s help came late in the process, after Marco had already taken off; and that was done more out of hatred for Crist than anything else.  Marco respects and likes Jeb, but he has never seen himself as indebted to him."

That quote is telling because it speaks to the fact that the debate over whether the idea that the two men would run against one another was ever accurate has transformed into a broader conversation of who owes who what.

For Rubio, disputing the idea that he had ever planned to defer to his political mentor (or even the idea that Jeb is/was a political mentor) is absolutely essential to his being taken seriously as a candidate.  That's especially true because Rubio, at 43, is the youngest candidate in the field. (Jeb is 62 years old.)

For Jeb, the way to win the "too close to run" conversation is to cast Rubio's candidacy as a sort of stepping stone to his political future -- a political future that doesn't include being the Republican presidential nominee in 2016.  "Rubio clearly hates the Senate and has little to lose (i.e. frontrunner for governor in 2018 if he decided to run)," wrote one Jeb ally in an e-mail to me.

The truth is we don't know the truth.  And, to the extent anyone does know whether Jeb and Marco ever talked about not running against one another or even believed that the other wouldn't run if he did is now lost forever amid what we now have: A race with both men in it.

So, what did I do wrong?  Make the assumption that because Rubio and Jeb were political allies -- successful establishment Republicans from the same state -- that meant they were close personal friends and, therefore, wouldn't run against each other no matter what.

As a reporter -- or even a source or strategist -- it's hard to know what's political and what's personal when it comes to politicians' relationships. Oftentimes, politicians find it in their best interests to give off the sense (or at least not disrupt the sense) that they are good friends with other politicians. That is, sometimes, true. Often, it's not. Or, it's true until their "friend's" interests runs into their own. Then, friendship -- even if it is genuine -- tends to take a back seat to political ambition.

Then there is the fact that open primary presidential races come along, at best, every four years -- and the allure of a chance to be the most powerful politician in the world is not the sort of thing governed by the same rules as calling "shotgun" to sit in the front seat of a car does. "The stakes are so big for the presidency that it is just an entirely different animal," said one Bush ally.

Regardless of the reasons, I got it wrong. I'll do better next time.