The one thing that might have stopped San Bernardino, that might have stopped 9/11 would have been stricter controls on those who came here.

If you want a candidate to defend life and marriage and religious liberty and the Second Amendment and to appoint strong constitutionalists to the court, I'm the only candidate with that record. That's why conservatives are uniting behind our campaign. And if they want to continue with the attacks, that's their prerogative.

Popularity isn't the end-all, be-all. What matters far more is that you stick to your principles, that you stand up and you live a life of integrity.

We see a missile here, a bomb there - looks good on CNN. This is nonsense. This is not a strategy of a serious commander in chief.

Any military force should be dictated by the vital national security interests of the United States. And if and when we use force, we should use overwhelming force for a clearly stated objective. And then when we're done, we should get the heck out.

Whatever the history of U.S. intervention in Iraq, our priorities now should be to protect our people and defend our national security interests, not to try to resolve an intractable religious divide some 1,500 years in the making.

Marco Rubio said he was personally open over a long period of time to offering a path to citizenship for immigrants here illegally. Rubio's work on a comprehensive immigration bill is one of his biggest vulnerabilities with Republican primary voters.