Rand Paul drops out of White House race
Republican Senator Rand Paul has dropped out of the race for US president after a disappointing fifth place finish in the Iowa caucuses.
Mr Paul often clashed with his Republican rivals over their hawkish views on foreign policy and their support of government surveillance.
He ended his bid in part to focus on his re-election to the US Senate.
He is seen as representing the Libertarian wing of the party, which promotes individual rights and privacy.
"Across the country thousands upon thousands of people flocked to our message of limited government, privacy, criminal justice reform and a reasonable foreign policy," he said.
"Although, today I will suspend my campaign for president, the fight is far from over."
Mr Paul, an ophthalmologist, represents Kentucky in the US Senate and is the son of former Congressman Ron Paul, who ran for president several times.
He has said in the past he is the right candidate to "stand up to both the right and the left".
Last year, a Time magazine cover labelled him "the most interesting man in politics".
There are now 10 Republicans left in the White House race, down from the original 17.
The 52-year-old hoped to gain the attention of young people hoping for change but was ultimately overshadowed by billionaire businessman Donald Trump.
Mr Paul is known for holding up the Senate floor for nearly 13 hours to delay the nomination of John Brennan as CIA director because of his opposition to the Obama administration's use of drone strikes against terrorists.
He also was criticised last year when he said vaccines could give children "profound mental disorders". He later said his children are immunised.
More on the race for the White House
- Rand Paul's elusive 'libertarian moment': Why 'the most interesting man in politics' never took off
- Winners and losers after Iowa vote: How Republican Senator Marco Rubio placed third but still won
- The Texan Tea Partier: Ted Cruz's rapid, rocky ascension to presidential candidate
- How does a US election work? If you want to be president, it helps to be governor, senator, or five-star military general - and have lots of patience
- Special report: The BBC's full coverage of the race to the White House
Mr Paul was passionate about criminal justice reform, saying the US needs to "break the cycle of incarceration for non-violent ex-offenders".
He was praised for level-headed debate performances, but ultimately was hurt by his non-interventionist polices after terrorist attacks in San Bernardino, California and Paris.
Mr Paul had trouble raising money for his campaign, as well, not attracting wealthy donors flocking to candidates like Marco Rubio, Jeb Bush and Ted Cruz.
With such a large field of candidates, underperforming Republican candidates are under increasing pressure to drop out of the race.
Former Governor of Arkansas Mike Huckabee dropped out on Tuesday as votes were being cast in Iowa.