Trump dominated both the polls and the media coverage through the summer and fall of 2015, and while he tussled with Bush, Carly Fiorina, and many of the other Republicans, Rubio flew mostly under the radar. It was a strategy that his campaign insisted was a deliberate choice, and as the Iowa caucuses rolled around, it looked like it was paying off. He fought hard with Cruz over immigration and parried attacks from Bush over his absences from the Senate, but he kept his distance—as much as possible—from the Trump circus. As other candidates fell away, Rubio surged into a strong third-place finish in Iowa, nearly eclipsing Trump. He was mocked by some for delivering a “victory speech” after coming in third, but if anyone left Iowa with a clear shot of momentum, it was Rubio.
All of that disappeared, however, on a debate stage in New Hampshire. Under fire from Chris Christie for relying on canned, 25-second soundbites, Rubio inexplicably respond with … the same canned soundbite. “This notion that Barack Obama doesn’t know what he’s doing is just not true. He knows exactly what he’s doing,” Rubio repeated over and over again, in a performance that was immediately likened to a malfunctioning robot.
Three days later, Rubio slipped to fifth place in New Hampshire, a finish that was blamed in large part on his debate debacle. He recovered in South Carolina, edging out Ted Cruz for second place in a state that seemed strong for the Texas senator. But he still could not come close to Trump, and in Nevada on February 23, the billionaire defeated Rubio by a nearly 2-to-1 margin.
With the race narrowed to five, Rubio finally went hard against Trump. Interrupting him frequently on the debate stage in Houston, Rubio unleashed months worth of opposition research and attacked Trump over his lack of policy depth, his use of immigrant labor, the lawsuit he’s facing over Trump University, and more. Trump staggered, delivering his worst performance of the primary season. The next morning, Rubio took it even further. In a planned departure from his stump speech that seemed like a cross between a Trump impersonation and a stand-up comedy routine, Rubio mocked the front-runner relentlessly. He made fun of him for misspelling words in his tweets, for applying makeup to his sweaty upper lip during a commercial debate in the debate, and for possibly checking to see if he had wet his pants. Later in the weekend, Rubio made fun of Trump for having “small hands.” “And you know what they say about guys with small hands,” Rubio said to shocked laughter from the crowd. “You can’t trust ’em!”
It was funny, sure. But many Republicans didn’t seem to know whether to laugh, cheer, or cringe. It also didn’t work. Trump upstaged Rubio by announcing the surprise endorsement of Chris Christie, and he proceeded to mock the Florida senator by calling him “little Marco” at rallies and debates. On Super Tuesday, Rubio was nearly shut out, winning only the Minnesota caucuses and watching as Ted Cruz eclipsed him as Trump’s main challenger. Rubio struggled, too, in the states that followed. He exited the race having won only in Minnesota, Puerto Rico, and the District of Columbia.