Rand Paul
Rand PaulReuters

Two Republican presidential candidates announced on Wednesday that they were dropping out of the race, two days after the Iowa caucuses.

The first candidate to drop out of the race was Kentucky Senator Rand Paul, who sent out a statement on the matter quoted by CNN.

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

Paul is expected to instead place his focus squarely on his Senate reelection bid, where he faces Lexington Mayor Jim Gray, who has the money to partially finance his campaign.

Paul finished a disappointing fifth place in Monday's Iowa caucuses, noted CNN, registering just 4.5% of the vote despite placing a heavy emphasis on the state's college towns to bring out younger voters inspired by his libertarian-minded message. He promised that night to continue his campaign.

Paul will not make an endorsement in the GOP presidential race before next week's New Hampshire primary, his spokesman Sergio Gor told CNN.

Sources close to Paul said a review of their results made clear to Paul that there was not a viable path to winning the Republican nomination and that fund-raising was becoming extremely difficult.

Later on Wednesday, former Pennsylvania Senator Rick Santorum also ended his presidential bid, two Republican sources told CNN.

He endorsed Senator Marco Rubio for the Republican nomination.

Santorum won the 2012 Iowa caucuses and ended that race with the second-most number of delegates to eventually GOP nominee Mitt Romney. But he was unable to capture any momentum this year, despite extensive barnstorming efforts in Iowa.