To the Editor: Take a trip down memory lane to understand why "When Campaigning is an Exercise in Altruism: In heavily Democratic Manhattan, Republicans are a near-extinct breed" (Oct. 23). Manhattan Republicans haven't offered Democrats serious competition for public office on any level in years. The citadel of liberal Republicans based in the East Side of Manhattan was totally eliminated years ago. Neighborhoods formerly represented by the late Congressman Bill Green, State Sen. Roy Goodman, Assembly Member John Ravitz and Council Members Charles Millard and Andrew Eristoff are now safely in Democratic Party hands. Crossover Democrats, who voted for former Presidents Reagan and Bush Senior, former Gov. Pataki and former Mayor Giuliani, along with Mayor Bloomberg, continue to move out of town, retire out of state or succumb to old age. There has been no successful GOP outreach to new Caribbean, Hispanic, Asian or other immigrant groups, or to middle class African Americans. For decades, once the GOP loses any incumbent City Council, State Assembly, State Senate or Congressional representative, they are never able to reclaim the district. Analysis of past election results revealed that both Pataki and Bloomberg had no coattails to elect any new GOP candidates from Democratic districts. Remnants of the Manhattan GOP would be better off taking the ferry to Staten Island, where Republicans, although outnumbered by more than two to one, have managed to remain competitive. Larry Penner Great Neck, N.Y. Letters have been edited for clarity, style and brevity.