WASHINGTON (AP) — Embattled Republican Herman Cain is pressing ahead with his White House bid, noting he has "attracted a little bit of attention" and defending his close ties to billionaire brothers whose organization bankrolls right-leaning causes.Cain gave a speech to Americans for Prosperity, headed by Charles and David Koch. The group has ties to the tea party and lobbies for lower taxes, less regulation and spending.He noted a New York Times story on the relationship, saying the newspaper was seeking to "attract more attention." Cain said he was "very proud" to know the Koch brothers. He said, "I am the Koch brothers' brother from another mother ... and proud of it."Cain's links to the Koch brothers could undercut his outsider, non-political image among people fed up with conventional politics.