Open this photo in gallery: Republican presidential candidates, (L-R) former U.N. Ambassador Nikki Haley, Florida Gov. Ron DeSantis and Vivek Ramaswamy participate in the FOX Business Republican Primary Debate at the Ronald Reagan Presidential Library on September 27, 2023 in Simi Valley, California.Justin Sullivan/Getty Images The second Republican presidential debate offered an audition for many things: public attention, meme-worthy moments, a favourable reception from donors, perhaps even the future direction of U.S. conservatism. What it did not offer was a chance to challenge the man who appears to have the party’s nomination already in his grasp. For the second time,…