(CNN) -- Sen. Sam Brownback of Kansas announced Friday afternoon that he is pulling the plug on his Republican presidential bid.
Sen. Sam Brownback ends his Republican presidential bid Friday. The senator was low on campaign cash.
"My yellow brick road just came short of the White House this time," Brownback said at a news conference in his hometown of Topeka, surrounded by his family and supporters.
The senator was not doing well in the polls and was heading into the primary season without enough campaign cash.
The senator did not offer an endorsement of any of his presidential rivals, but he said he plans to discuss a possible endorsement with some of those candidates. Watch Brownback say what it takes to win »
Brownback said his uphill struggle to get media exposure in the crowded GOP field made it difficult for him to raise enough money to stay in the race, especially with spending "swooping up" headed into January's Iowa caucuses.
"We're out of money," he said.
The senator said a turning point in his campaign came in August, when he finished third in a Republican straw poll in Ames, Iowa, even though three of the top-tier candidates didn't participate. Brownback, who had hoped to finish in the top two, said his fundraising began dropping after Ames.
Earlier this week, Brownback reported raising just $926,000 in the third quarter of the year. The latest CNN/Opinion Research poll on the Republican race put his support at just 1 percent.
Brownback, 51, an outspoken opponent of legal abortion, had hoped to make himself the choice of the social conservative wing of the Republican Party, which has yet to embrace any of the GOP front-runners. But he said that support didn't materialize as early as he hoped it would.
"I think we had a good strategy. I was very hopeful we'd be able to get the social conservative wing of the party on board early and then build out to the economic conservatives," he said. "I don't think conservatives are divided. I just think they're undecided."
However, he also admitted that the high-profile debate on an immigration reform bill in the Senate this summer did not help his presidential campaign. His support for the bill angered some conservatives in the GOP base, who charged the measure amounted to providing "amnesty" to illegal immigrants.
Brownback said he plans to return to the Senate, where he has about three years left in his current term. He apologized to Kansas voters for the votes he missed while campaigning for president.
"But I'm back now, and I look forward to working with all of you to build a stronger state," he said.
Brownback's departure leaves eight candidates in the GOP presidential race: Former New York City Mayor Rudy Giuliani, former Sen. Fred Thompson of Tennessee, former Massachusetts Gov. Mitt Romney, former Arkansas Gov. Mike Huckabee, Sen. John McCain of Arizona and Reps. Duncan Hunter of California, Ron Paul of Texas and Tom Tancredo of Colorado. E-mail to a friend