BOGOTA, Colombia (AP) — Colombia’s largest remaining rebel group on Monday declared a unilateral ceasefire ahead of next month’s high-stakes congressional elections, which have already been marred by acts of violence against candidates in rural areas. The National Liberation Army, or ELN, said in a statement published on its website that it will cease attacks against military and electoral authorities to allow for people to vote “in liberty,” but did not clarify when the ceasefire would end.