When it was reported that Sen. Marco Rubio hated being in the U.S. Senate and was running for president because he was “frustrated” with how that chamber of Congress worked, it took me back to 2012, when I first caught wind of this frustration he had with the governing body in which he was elected to serve.

Rubio never did like the Senate, according to his close friends, who divulged this information only a year after he took office. Marco Rubio himself said, “I don’t know that ‘hate’ is the right word… I’m frustrated.”

When Donald Trump poked him for missing so many votes in the Senate, Rubio went on the defensive and spoke candidly about the reason for his missed votes. He explained, “That’s why I’m missing votes. Because I am leaving the Senate. I am not running for reelection.”

Rubio’s words and honesty could turn out to sting him with voters—voters who already feel betrayed by his broken campaign promise that he would not support a pathway to citizenship for illegal immigrants.

Rubio co-sponsored and promoted the now infamous and disastrous Senate “Gang of Eight” comprehensive immigration reform bill in 2013.

Rubio is now being called a quitter.

Is it fair to call him that? Probably.

Floridians donated, volunteered, and some even bled to get Rubio elected, all because they believed that Rubio would follow through with all that he promised to accomplish in the U.S. Senate.

Rubio knew what to expect if elected. One of his mentors and supporters at the time was then-Senator Jim DeMint, who told reporters at the 2011 CPAC that he had already informed Rubio about how the Senate worked and what to expect.

So, Rubio knew what he was getting himself into, and he is probably just frustrated by the fact that then-Senate Majority Leader Harry Reid (D) would block bills coming over from the Republican-led House of Representatives, leaving him and other Senate Republicans “frustrated” and sitting on their hands.

Now that Republicans control both the Senate and House, the legislative gridlock continues, as just about any meaningful legislation that either chamber proposes is threatened by a presidential veto, leaving Rubio and the rest of his colleagues in the Senate with no other recourse.

Republicans just don’t have enough support to override the president’s pen.

OK, we get it. But for Rubio to tell the American people that he is quitting the job he was elected to do out of simple frustration, is a deal-breaker for many voters.

If Rubio didn’t like the Senate and is quitting, what is to say that he won’t do the same if elected president?

Expect Rubio’s detractors, especially Donald Trump, to pounce on him over every word.