Sen. Jesse Helms, a leading spokesman for conservative Republicans, has endorsed commentator Bruce Herschensohn in the crowded GOP primary for a chance to oust Democrat Alan Cranston from the U.S. Senate. The North Carolinian passed the word of his endorsement at a fund-raising reception in Costa Mesa over the weekend. He said he does not have anything against others seeking the GOP nomination--including Rep. Bobbi Fiedler, recently indicted on charges she tried to bribe state Sen. Ed Davis to drop out of the race--but called Herschensohn the candidate with the best understanding of conservative issues like defense spending. "The Senate is a Republican Senate by a narrow margin," Helms said. "But it is not a conservative Senate. To prevent Ronald Reagan from having to take half a loaf, we need seven to 10 more conservatives."