By DAVID KLEPPER and CHRISTINA A. CASSIDY WASHINGTON (AP) — Hacking a local election system in the United States wouldn’t be easy, and secretly altering votes on a scale massive enough to change the outcome of the presidential race would be impossible, election officials have said, thanks to decentralized systems, paper records for nearly all ballots, exhaustive reviews, legal due process and decades of work by American election officials, volunteers and citizens. But foreign actors and domestic extremist groups looking to meddle in next week’s election can target a much weaker link: voters’ perceptions and emotions.