David Jackson and Josh Hafner, USA TODAY

Joseph Gerth, The (Louisville) Courier-Journal

Kentucky Sen. Rand Paul, who had hoped to ride libertarian support to the Republican presidential nomination, withdrew from the race after a fifth-place showing in the Iowa caucuses.

“It has been a privilege to give voice to the liberty movement in this race, and I believe we have broadened the debate by being part of it," Paul said on Fox News. "Although today I will suspend my campaign for the presidency, I will continue to fight on for liberty, for the Constitution, for justice in the United States Senate."

Paul, 53, is running for re-election in November to a second Senate term. Wednesday morning, he posted this video thanking his supporters on Twitter:

"I’m proud of our principled campaign and the thousands of young people that have been energized by our message of limited constitutional government. Ours has been a unique voice int his race," Paul said.

While he entered the presidential race on a wave of publicity, Paul could not build the kind of support that fueled the candidacies of his father, former Texas congressman Ron Paul, who ran as a Libertarian in 1988 and sought the Republican nomination in 2008 and 2012.

During the campaign, Rand Paul did not hesitate to attack Republican opponents over issues like government spending and surveillance programs. Opponents did not hesitate to return the favor, saying Paul's views would undermine national defense.

Rand Paul dropping 2016 presidential bid

One of those rivals, though, paid tribute to Paul as he exited the race Wednesday,

"Rand is someone I disagree with on a lot of issues, but as I said the other night at the debate, he actually believes strongly in what he stands for and I respect that," said Florida Sen. Marco Rubio.

Paul failed to gain momentum in polling throughout the race, averaging 2.4% nationally, according to the most recent rolling average of polls from RealClearPolitics. He was relegated to the undercard at the Jan. 14 South Carolina debate, which he skipped, before rejoining the main stage at the Jan. 28 Des Moines debate.

Paul also was running out of money. His most recent filing with the Federal Election Commission showed that at the end of 2015, he had less than $1.3 million in his presidential campaign fund.

Paul's exit now means he won't be around for Kentucky's March 5 Republican presidential caucus, which party leaders instituted at his behest to allow him to circumvent a law that prohibits candidates from appearing twice on a primary or general election ballot in most situations.

Paul agreed to pay the estimated $500,000 cost to hold the caucus. Mike Biagi, executive director of the Republican Party, said that Paul has raised $250,000 for the caucus and the party is currently working on updated cost estimates for it and is confident Paul will raise whatever is needed.

Marcus Carey, a Northern Kentucky Republican who opposed the caucus because he worries that it will confuse and disenfranchise voters accustomed to voting for presidential nominees in the May primary, said Paul's withdrawal underscores why it was wrong to approve the caucus in an effort to appease Paul.

"I'm sorry his bid for the president seems to have come up short, but I think that this always had to at least have been recognized as a real possibility from the beginning," he said. "Now that it has come to fruition, we're stuck with this process that disenfranchises people."

Scott Lasley, a political science professor at Western Kentucky University, who headed the committee that advised party leaders on the caucus, said that whether the caucus is a success or failure will be decided by voter turnout and whether candidates come into Kentucky to campaign, which he said was at the forefront of the minds of some who supported the caucus.

Lasley said that Paul's withdrawal could even help the Kentucky caucus lure candidates to the state, saying "there is ironically an inverse relationship" between Paul's success and participation by others. "If he was a front-runner coming into Kentucky, he'd clean house easily. The fact that he was not able to do better, I think it made Kentucky more attractive to the other candidates."