5 Things That Ultimately Doomed Marco Rubio's Presidential Campaign

— -- Marco Rubio was once the dubbed "The Republican Savior," but on Tuesday he suspended his campaign after a devastating loss in his home state of Florida. What went wrong?

The son of a bartender and a maid -- both Cuban immigrants -- Rubio was young, charismatic, a great speaker with a compelling personal story. After a disappointing showing among Hispanic voters in 2012, Rubio’s background seemed a particularly good fit for 2016.

After a meteoric rise in Florida politics, Rubio rode the Tea Party wave to the Senate in 2009. And during his presidential campaign, Rubio himself repeatedly made the case that only he could unite and grow the party. In short, his campaign seemed to have many of the right ingredients for success. But after his loss Tuesday, his White House hopes were quashed.

Here are the top five things that ultimately doomed his campaign:

1. The 'Rubio Robot' Moment

It was an attack he should have seen coming a mile away. During the ABC News debate in Manchester, New Hampshire, in February, Chris Christie, who had been going after Rubio for weeks, again argued the Florida senator was too young and unprepared to be president.

Rubio refused to engage -- he tried to pivot and attack Obama instead. In doing so, however, Rubio began repeating the same lines.

“Let's dispel with this fiction that Barack Obama doesn't know what he's doing. He knows exactly what he's doing,” Rubio said again and again.

Christie pounced on Rubio for his "memorized 25-second speech." Rubio ended up repeating the same line, almost verbatim, four times.

The candidate who had always been praised as a great speaker was now being called robotic. Over the next few days -- the days leading up to the New Hampshire primary -- it was all Rubio would get asked about. What happened? Did he freeze? How was he not better prepared to fight back? Twitter was abuzz. Rubio even had people dressed as robots come troll him at various campaign events.

Without a doubt, the meme slowed Rubio’s momentum from Iowa and contributed to a disappointing fifth place finish in the Granite State.

2. The Personal Attacks

Rubio spent most of his campaign trying to stay above the fray, arguing he wanted to run a campaign his children would be proud of, one that was worthy of the office he was seeking.

He spent the summer avoiding Donald Trump, only commenting on his inflammatory rhetoric when specifically asked to respond. Even on policy, it would sometimes be days before Rubio would comment. He argued if he spent all his time responding to what Trump was saying, his entire campaign would be consumed by it. Trump never really went after Rubio, so Rubio stayed away.

It wasn't until the heated GOP debate in Houston that Rubio would truly engage. He called out Trump for not having outlined any specific policy proposals. The field had winnowed down enough, his advisors said, that only now did it make sense to take on Trump.

The day after the debate marked a shift in strategy for Rubio. All of a sudden, he began mocking Trump's misspelled tweets, his hair, his tan. He even suggested Trump had wet himself at the debate. Asked about Reagan's 11th commandment, which states Republicans shouldn't attack each other, Rubio shot back that it didn't apply to Trump.

The attacks reached a climax when Rubio said this of Trump: "You know what they say about a man with small hands."

The strategy backfired. Rubio's supporters, who appreciated the dignified campaign he ran, grew disappointed. Many turned to Kasich, and Rubio dropped in the polls.

Rubio eventually said that he regretted his personal attacks on Trump, that he had embarrassed his wife, children and supporters. But he said he had learned growing up that when a bully punches you in the face, at some point, you have to hit back. He maintained he would continue going after Trump on policy differences because voters deserved to know about those. But the damage was done.

3. Not Winning

Rubio began the year with a strong third place finish in Iowa. He exceeded expectations by essentially tying Trump, who came in second. He was third -- yet he was the surprise, he was the story, he had the momentum.

The “Marcomentum” was short lived. Rubio lost it when he lost New Hampshire. He somehow managed to regain a portion of it in South Carolina, with the endorsements of the state’s popular Gov. Nikki Haley, Sen. Tim Scott and Rep. Trey Gowdy. But even then, Rubio finished 10 points behind Trump. It was a victory for the campaign in that they beat Cruz, though only by a very slim margin.

Nevada came and went without much ado (Rubio was second), but by the time Super Tuesday rolled around, Rubio had yet to win a single state. Rubio argued that only he could unify the party to stop Trump, that the field needed to winnow down and consolidate behind him. The Cruz campaign, meanwhile, was touting its win in Iowa, arguing Cruz was the only candidate who had actually proven he could beat Trump.

The media was now questioning non-stop when Rubio would start winning and realizing the potential he seemed to hold. But there were no states voting on Super Tuesday that were locked in for Rubio. So Rubio touted delegate count. He said first place finishes didn't matter, that it was delegate count that did. The SEC primary states, with their large share of evangelical voters, were always going to be Cruz’s, Rubio said. But delegates would be awarded proportionally, and wins wouldn’t start to matter until they got to the winner-take-all states.

He came out of the biggest day of the season with just one win -- his first -- in Minnesota. He started getting shut out of delegates altogether in certain states (he failed the meet the 20 percent threshold). As pressure mounted on candidates to drop out and consolidate behind someone to stop Trump, all eyes turned to Florida and the winner-take-all states. Expectations -- that Rubio set for himself -- were rising. But by then the narrative that he couldn’t win had taken hold.

4. The Foil That Never Was

When he first ran for Senate in 2009, Rubio was a sensation -- the underdog in the race against Charlie Crist, then the highly popular sitting governor of Florida. Rubio was down double digits when the race first began. The “entire Republican establishment lined up against me,” Rubio often recalled out on the trail, adding he was told he should wait his turn and get in line.

This time around, the Rubio team assumed there would be a repeat of that. Rubio would be up against Jeb Bush, the establishment’s pick and his former mentor. His entire campaign was built on the idea that 2016 would be a “generational choice,” that he would be the fresh face to first defeat Bush, and later Hillary Clinton. He would again be the underdog.

But Bush’s candidacy failed to take off and left Rubio without real foil. He was likable, everyone’s second choice. He still had to put up with $40 million of attack ads from Bush’s campaign, but when he couldn’t be the underdog, Rubio failed to develop a true identity. And all the while, the party was undergoing such turmoil that it would prove difficult for Rubio to make the case that he would be the better general election candidate up against Hillary Clinton. By the time the campaign changed its strategy to become the face of the anti-Trump movement, it was too late.

“America is in the middle of a real political storm, a real tsunami. And we should have seen this coming,” he acknowledged during his concession speech.

Rubio was never a movement. Though he was always on message and rarely flip-flopped, he failed to build a coalition of voters that would stick with him when times got tough. He had his fair share of supporters, but he was never able to generate the level of enthusiasm that Trump could. Rubio’s biggest rally averaged about 8,000 people, while Trump has consistently seen 20,000 people show up.

5. The Inexperience Problem

Rubio spent the early stages of his campaign trying to fight off the idea that he was too young. In New Hampshire and Iowa especially, as he introduced himself to the nation, a lot of voters wanted to know how he was any different from President Obama, who was also a freshman senator and a great speaker when he launched his campaign in 2008.

Rubio argued that the reason Obama had "failed" was not because he didn’t have enough experience, but because his ideas don’t work.

In New Hampshire, voters wondered if someone with more executive experience -- a governor -- might be better. During the confrontation with Christie, Rubio also failed to identify his accomplishments. And in one buzzy moment, Rick Santorum, who endorsed him, was asked to name some of Rubio's accomplishments. He couldn’t cite even one.

The one thing people remembered Rubio for was an immigration proposal that would have provided a legal pathway to citizenship for undocumented immigrants. It had earned him praise in 2013, and was cited as one of the elements that might make Rubio a strong general election candidate. But it was a measure that, of course, a majority of primary voters rejected. Some questioned whether he had run from his own signature bill when he made the assessment that it might hurt him on his way to the White House, and his supporters were disappointed once again.