US Republican presidential candidate Rick Santorum has ended his campaign for the party’s nomination following disappointing results in the Iowa caucuses.

The former Pennsylvania senator, who won Iowa in 2012, declared an end to his presidential aspirations Wednesday, after finishing at 11th place in the Hawkeye State with just one percent of the Republican vote.

He struggled in a year dominated by blunt-spoken billionaire businessman Donald Trump, and more recently by Senator Ted Cruz of Texas, who won Monday's caucuses.

Appearing on Fox News on Wednesday, Santorum threw his weight behind Senator Marco Rubio of Florida, whose star is on the rise.

"We decide to support Marco Rubio," he said.

Santorum said that he and his family decided that the best way to promote his campaign’s message was to support someone “who shared those values and is in a better position to do well in this race."

Religious freedom, social conservatism and the fight against extremism were the pillars of Santorum’s campaign.

Senator Rand Paul of Kentucky also dropped out of the race for the White House on Wednesday.

"It's been an incredible honor to run a principled campaign for the White House," Paul said in a statement. "Today, I will end where I began, ready and willing to fight for the cause of liberty."

Paul had launched his bid for the White House looking to expand the libertarian base that his father, Ron Paul, built into a powerful coalition.

Paul said while his campaign was over, his commitment to “fight for the cause of liberty” was not.

“Across the country, thousands upon thousands of young people flocked to our message of limited government, privacy, criminal justice reform and a reasonable foreign policy. Brush fires of liberty were ignited, and those will carry on, as will I,” he added.

Mike Huckabee, the former Republican governor of Arkansas, suspended his campaign on Monday night hours after the Iowa caucuses.

Despite the suspensions, the Republican filed is still crowded with nine candidates vying for the party’s nomination.