Republican Rick Santorum suspended his 2016 presidential campaign Wednesday following a poor showing in the Iowa caucuses.
The former U.S. senator from Pennsylvania also endorsed Sen. Marco Rubio of Florida for the GOP nomination. He called Rubio a "born leader," saying he had an "optimistic" message.
Santorum first announced the decisions in a Fox News interview on Wednesday night.
Santorum's departure comes after Sen. Rand Paul of Kentucky dropped out earlier Wednesday. Former Arkansas Gov. Mike Huckabee also suspended his campaign this week.
Nine Republican candidates remain in the race.
Santorum, who won the 2012 Iowa caucus, finished near the bottom of the pack on Monday as conservatives gathered around Sen. Ted Cruz of Texas. He gathered only about 1 percent of the vote.
Santorum's campaign committee had roughly $13,000 on hand at the end of 2015, according to Federal Election Commission data released this week.
— The Associated Press contributed to this report.