Republican Tom Tancredo has pulled out of the race to become the party's candidate for US president.
Tom Tancredo forced Republican candidates to debate immigration
The five-term congressman from Colorado has repeatedly trailed the rest of the Republican field in opinion polls.
Mr Tancredo had campaigned on a tough anti-immigration platform, running campaign adverts linking illegal immigration to terrorism and rape.
He will now back Mitt Romney, and said he hoped by withdrawing he would not split Republicans over immigration.
Confirming his withdrawal, Mr Tancredo said he did not want to split the field and allow a candidate with a moderate take on the issue to secure the party's nomination.
"I fear remaining in this race, one which I cannot win, would contribute to the nomination of one of these candidates," he said.
He highlighted Mick Huckabee and John McCain as two candidates whose policies on immigration did not meet with his approval, the Associated Press reports.
"We have done too much, we have come too far for me to allow that to happen," Mr Tancredo said.
His move comes just two weeks before the Iowa caucuses, the first step for both Republicans and Democrats in choosing their presidential candidates.