The Millers manager made an enquiry about Showunmi this week, but his initial approach has been rejected with the 27-year-old keen to battle for his place at Leeds.
But Moore may return with a fresh move for the former Bristol City and Luton Town forward, who he is a long-time admirer of, before the loan deadline on November 26.
Moore was hoping to watch over the Nigerian international in the Whites' Johnstone's Paint Trophy quarter-final clash with Grimsby on Tuesday evening, but he only featured for the final few minutes in the 3-1 victory after coming on as a sub for the tenth time this term.
Moore said: "We've made an enquiry, but I think he wants to stay where he is at the moment."