In the past ten months, Sen. Marco Rubio (R-Fla.) has gone from being someone I predicted would be elected president in 2016, to someone I now think might be on New Jersey Governor Chris Christie's "veep" short list.

If you're keeping score, that's a demotion.

If Rubio's year began with a profile in courage (immigration reform), it's ending with a profile in cowardice (his support of the defund ObamaCare strategy). Along the way, he managed to disappoint an incredibly wide swath of conservatives, ranging from tea party folks to establishment RINOs. How did this happen?

Let's begin with his decision to champion immigration reform. It was a move that many of us thought was important following Mitt Romney's loss last November. It was both gutsy and risky, and, for many, it was tantamount to Rubio crossing the Rubicon.

Grassroots conservatives are passionately opposed to a pathway to citizenship, yet for months, Rubio fought the good fight, explaining to conservative talk radio hosts why this policy would be good for all Americans.

But what started out as a fight turned into a bar brawl. Having once been the darling of the tea party, Rubio found himself falsely accused of wanting to give illegal aliens free cell phones (which were dubbed "Marco Phones" by some.) The Heritage Foundation, a group headed by Rubio's friend and mentor Jim DeMint, ran ads attacking him. He was called a RINO and a sellout — and was even protested in Florida by tea party folks who dubbed him "Amnesty Man."

Few of us could sustain this kind of unrelenting criticism — from our home base! — without it taking a toll. And eventually, it did.

Once the Senate passed the bill it became clear that House passage would be an even bigger hurdle, and Rubio seemed happy to move on to greener pastures. And who could blame him?

He had expended much political capital on immigration reform. If he wanted to maintain his status as a conservative, he would need to mend some fences. And fast.

It's not uncommon for this sort of rebuke to cause politicians to reevaluate their image. Sometimes, this has historic implications. After losing a race in 1958, George Wallace declared he would never be "outniggered" again. Twenty years later, after losing a Congressional bid, George W. Bush would reportedly declare that he would never be "outcountried" again. After the immigration push, Marco Rubio seems to have decided he would never be "outconservatived" again.

For the first time in a long time, he had lost control of his own message. And so, like a man skidding on ice, he overcorrected.

I'm not suggesting Rubio actually changed any of his positions. Instead, he ratcheted up the rhetoric, as if to remind everyone: "I'm a tea party conservative, too!" And he signed on to well-meaning, if unachievable, objectives. One of the ideas he embraced was the idea that we could defund ObamaCare.

Rubio has always been an opponent of ObamaCare, so his opposition to the law should come as no surprise. However, as someone whose brand was as an eloquent, serous conservative, his championing of a strategy which was so flawed that even I predicted its disastrous denouement — as early as July — was interpreted by many observers as a transparent act of shameless pandering.

Once known for soaring speeches, Rubio's voice now turned to demagoguery. He even went so far as to declare, "I don’t think you can say you are against ObamaCare if you vote for a budget that funds it." This, of course, raised an obvious question: Did Senator Rubio support every single line item in every budget he has ever voted for in the past?

To be fair, he probably never dreamed it would get this far. He thought that he was just checking off the "conservative cred" card, and that some other RINO fall guy — probably House Speaker John Boehner — would bail him out by caving. They didn't. Instead of this being some minor blip on the radar, the defund effort caught fire, leading to the government shutdown, and eventually to today.

It turned out to be a high-profile debacle, and one gets the sense he didn't see that coming.

And so, the defund strategy seems to have helped define him almost as much as the immigration reform push. In the wake of the government shutdown, he has now been lumped in with "Washington," and all the dysfunction and incompetence that entails.

You can't be all things to all people. In politics, it's almost a flaw to want everyone to like you. Let's be honest: If Rubio does run for president in 2016, the notion that Tea Party conservatives in Iowa or South Carolina will now support him is absurd. First of all, they won't forgive him for the immigration thing. And second, even after championing the defund strategy, why would they choose him over Sen. Ted Cruz (R-Texas) or Sen. Rand Paul (R-Ky.)?

Even in his home state, though, there are signs his stock is plummeting. His approval rating among Florida voters has dropped this month to 43 percent, with 45 percent disapproving. That's down from a 51 percent approval rating, with 33 percent disapproving, just over a year ago.

When you try to please everyone, you end up pleasing nobody. And so it is.

But I can't help wondering what would have happened if Rubio had stood up to his conservative colleagues, as Sen. Kelly Ayotte (R-N.H.) did? In the short term, he would have taken even more heat from the people who won't support him any way. In the long run, however, he might have arisen as a sane, serious conservative who was willing to demonstrate leadership and stand up for it no matter the cost. Instead, Rubio looked like a follower — someone who was goaded into supporting a stand by the more powerful conservative leaders in the Senate. And these optics pose a serious problem for a man who ostensibly wants to be president. Presidents shouldn't be susceptible to peer pressure. If he can't stand up to Cruz, how can he stand up to Putin?

(Note: In fairness to Rubio, in championing the defund strategy, he mostly avoided the kind of internecine attacks which made this an especially ugly fight. It wasn't Rubio who ran ads attacking other Republicans, and it wasn't Rubio who called people who disagreed "the surrender caucus" or compared them to Nazi appeasers. For this reason, his relationships with donors and his Senate colleagues is probably still quite strong.)

Ironically, the flawed defund strategy also highlights a flaw in Rubio's strategy. A couple months ago, I wrote that the 2016 Republican primary would be like an NCAA tournament. The way into the final round was to win your "division." Cruz and Paul, I argued, would have to compete to see who "owns' the tea party division, and that Christie and Rubio would compete to win the more establishment conservative bracket. Cruz and Paul had nothing to lose by supporting the defund effort. It merely reinforced their brand. But Rubio didn't seem to grasp that he could never be the tea party guy — that his brand was being a serious, thoughtful, conservative.

He seems to get this. Now. You don't see Marco Rubio talking much about defunding ObamaCare, or much else these days. Based on the last few months, keeping a low profile seems like a wise idea. He's too talented for this to destroy him. One hopes this was a learning experience.

But by underestimating how tough immigration would be, and misunderstanding how far the defund strategy would go, Marco Rubio's fortunes have dropped further than any other likely 2016 presidential candidate. So far, 2013 has been Rubio's unlucky year.