Sen. Rand PaulRand PaulLawmaker seeks to investigate Obama's foreign tax compliance law Funding bill rejected as shutdown nears GOP senators hit FBI on early probe of NY bombing suspect MORE (R-Ky.) is suspending his campaign and dropping out of the presidential race.
"It's been an incredible honor to run a principled campaign for the White House. Today, I will end where I began, ready and willing to fight for the cause of liberty," he said in a statement.
The decision follows a disappointing finish in the Iowa caucuses, where Paul won just 4.5 percent of the vote, good for a fifth place showing.
He's also faced criticism from some Republicans who want him to focus on his Senate reelection bid in a year where Democrats are threatening to retake the upper chamber.
Paul has struggled with lackluster fundraising and polling that has kept him on the bubble of the GOP main debate stage. He boycotted the Fox Business undercard debate in January after failing to make the main stage but squeaked back into primetime for a Fox News debate later that month.
Paul is the second GOP casualty of the Iowa caucuses. Former Arkansas Gov. Mike Huckabee dropped out of the race Monday night after finishing in a tie for ninth place in Iowa.
Paul would have been a longshot to make this Saturday's ABC News debate, which does not include an undercard portion.
The main stage will include the top three finishers in Iowa, as well as the top six candidates both in national polls and in polls of New Hampshire voters. By Wednesday morning, Paul sat in seventh place in the RealClearPolitics (RCP) average of national polls and in ninth place in RCP's New Hampshire polling.
His statement adds that his "fight is far from over" and signaled a shift towards his Senate reelection bid.
"I will continue to carry the torch for Liberty in the United States Senate and I look forward to earning the privilege to represent the people of Kentucky for another term," he said.
Paul ends his bid with just $1.3 million in the bank, a small sum for a presidential race but a meaningful addition to a Senate campaign account.
He'll likely be able to roll a significant portion of that over into his Senate reelection bid once he pays off almost $250,000 in debt and returns any donations marked for the general election. The remaining sum can be transferred to his Senate campaign account.
Since the transfer only includes the most recent donations, Paul hasn't boxed himself out of relying on older donors. If a presidential donation has already been spent, the donor can give again to Paul’s senatorial campaign.
Lexington Mayor Jim Gray, seen as the Democrats' top challenger to Paul, announced last week that he would run for Paul's seat.
Conservative groups Club for Growth and Freedom Works have both endorsed Paul’s reelection bid.
Here's the full statement from Paul announcing his decision:
"It's been an incredible honor to run a principled campaign for the White House. Today, I will end where I began, ready and willing to fight for the cause of Liberty.
"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. Brushfires of Liberty were ignited, and those will carry on, as will I.
"Although, today I will suspend my campaign for President, the fight is far from over. I will continue to carry the torch for Liberty in the United States Senate and I look forward to earning the privilege to represent the people of Kentucky for another term."
Updated at 11:00 a.m.