What do you think are Rubio's fatal flaws?
Besides being republican?

But seriously, I think it's more of a republican fatal flaw regarding Rubio. There is this idea that Rubio is somehow going to attract "hispanics" or "Latinos." Truth is, Rubio is far more divisive for "hispanics" and "Latinos" than republicans have blamed Obama for being. Rubio is of Cuban decent. The Cuban story is completely different than any other group of people lumped in to the "hispanic" or "Latino" categories. Cubans have a different experience in the U.S. I'm sure you've heard of the wet Feet - Dry feet policy. Any Cuban that makes it onto U.S. soil gets to stay and a year later they get to apply, and receive permanent resident status. They can then go ahead and become citizens some time later. No other group of "hispanics" or "Latinos" gets to do that. Everyone else remains an illegal immigrant. To others, the treatment that Cubans get is unfair. It appears to be preferential treatment for one particular group. It's also one of the smaller groups of people that fit into the "Hispanic" and "Latino" categories.
So the republican idea is that this guy who is young
1 and relatable to "hispanics" and "Latinos." Except, he isn't actually relatable. He is a sign of republican hypocrisy. Republicans rant against illegal immigration, but here is a group of people who is not only encouraged, but rewarded for illegally coming into the U.S. And not a single republican has spoken out against this policy. Worst of all, now that the Obama administration is trying to normalize relations with Cuba, you get people like Rubio saying how evil an idea that is. To other "Hispanics/Latinos" it seems more as if Rubio is trying to keep the status quo with Cuba because normalizing relations with Cuba might lead to Cubans losing their preferred immigration status.
The republican party might be looking at Rubio as their great "Hispanic" hope, but he isn't. He will just remind others how their family and friends are seen as Trump put it, being rapist, while Cubans are given everything. Not rally the image republicans think Rubio is putting out.
Then there is the whole Braman funding thing. Norman Braman is one of the local billionaires who has supported Rubio over the years. By supported I don't only mean given to his political campaigns. The guy has given fake jobs and paid Rubio and his wife. He pretty much owns Rubio. You may not have seen much about that yet, but let Rubio get a bit more traction, and you'll see it all over the news.
On a personal note, I can't stand Rubio because of his amazing hypocrisy. He is the guy that when he was in the Florida legislature, pushed to cut higher education funding. I remember at my university a lot of programs were cut. They were completely eliminated. Lots of universities had to cut funding. Then, as soon as he left the Florida legislature, he took a "job" at my university "co-teaching" a class. He got paid something like $70,000.00 to co-teach a class. If he was going to teach the class, great, but co-teach? Really? We could have probably hired a good professor for the kind of money Rubio is getting. One that would at least teach his own class.
[sblock=1]I was standing in line at the Starbucks at my university, and the guy is going bald. He also wears mom jeans, and his pants appear to be making a run for his chest, as do the pants of old men.[/sblock]