AP/Carolyn Kaster
Sen. Marco Rubio (R-Florida).
Rubio reportedly made the comments in a conference call with his top donors, where he said he feels "uniquely qualified" to run for the White House under the Republican banner.
According to the AP, Rubio also took a swipe at Democratic front-runner Hillary Clinton, who announced her own presidential campaign on Sunday.
"Rubio said the former first lady 'is a leader from yesterday,'" the AP's Philip Elliott and Brendan Farrington wrote. "Rubio says he has always felt the United States is about tomorrow."
Rubio's campaign team did not immediately respond to a request for comment from Business Insider. The senator was expected to make his 2016 intentions clear at a "big announcement" event scheduled for Monday evening at Miami's historic Freedom Tower.
Rubio would be the third major Republican presidential candidate to officially declare his presidential bid. Two of his colleagues, Sens. Rand Paul (R-Kentucky) and Ted Cruz (R-Texas), recently announced their own campaigns.
This post will be updated with additional information. Last updated 11:04 a.m.