Out on the trail, Rubio often brings up his Senate campaign. He was down double digits when the race first began but later made an impressive comeback and went on to win in a landslide.
“The entire Republican establishment lined up against me,” Rubio often recalls, adding he’d been told to wait his turn and get in line.
“I didn’t know there was a line!” he often says.
“Too many of our leaders and our ideas are stuck in the 20th century,” Rubio said at his campaign announcement in April last year.
But Bush’s candidacy failed to take off -- and left Rubio without a real foil.
Now, Rubio is again trying to position himself as an underdog.
“We're an underdog, there’s no doubt about it,” he recently told ABC’s Tom Llamas in Shelby Charter Township, Michigan. “And you know what? America is a nation of underdogs. I've always been an underdog.”
But in the year of the outsider, that argument doesn’t really hold up. Rubio now has more Congressional endorsements than any other Republican candidate, and it could be argued that this time around, it’s Trump -- and maybe even Cruz -- that are underdogs in their own right, given the extent to which they are being criticized by the establishment.
Rubio has now tweaked his message to sell himself as the one candidate able to unite the party -- the face of the anti-Trump movement. (It's common to see "Anybody But Trump" and "#NeverTrump" signs at Rubio rallies now.)
“In 2009, I was arguing that the person running as a Republican was not a Republican, that the person masquerading as a conservative was not a conservative,” he said in Jacksonville, Florida over the weekend.
"It’s funny how history repeats itself," he added.