A formal public announcement in Miami is expected later in the day.
In the meantime, here are six things many don't know about the Florida Republican, revealed in his 2012 autobiography, "An American Son."
He was almost born in Cuba: Rubio's family emigrated to the U.S. in 1956, before the rise of Fidel Castro, and briefly returned to Cuba after the revolution with thoughts of returning permanently. They had become discouraged by the difficulty of life in the U.S. On a visit to Cuba in 1960, relatives warned them not to stay, and they returned to the U.S.
He was a self-described spoiled brat: Born in Miami in 1971, Rubio was a late addition to the family. His parents, who were in their 40s at the time, already had two older children. He acknowledges being spoiled as his parents tried to provide for the family. He recalls childhood tantrums over delays in being served his after-church pancakes at an IHOP restaurant. Rather than admonish Rubio for his impatience, his father politely asked if the waitress could hurry it up.
He was a so-so student. After graduating from high school with a 2.1 grade point average and attending a small Missouri college to play football, Rubio transferred to a community college in southern Florida, improved his grades and eventually graduated from the University of Florida and the
He was Mormon: The family relocated from Miami to Las Vegas when Rubio was a child as he father sought bartending work. There Rubio joined his dad on the picket line during a labor strike against the casinos. The family briefly became Mormon. Rubio urged his father to quit smoking and complained that working in a bar was "sinful." Today, Rubio is a practicing Catholic.
His first career choice was the NFL: Rubio, a longtime fan of the
He loves hip-hop: Turning up the Tupac is among Rubio's guilty pleasures.