Washington — Senate Democrats on Tuesday tried to force a vote on a measure to prevent President Trump from launching a military attack on Cuba, as he repeatedly threatens action against the island.  But Republicans blocked the procedural vote from moving forward, arguing that the U.S. isn't engaged in hostilities with Cuba. The issue is "moot," GOP Sen. Rick Scott of Florida said.  Democrats are seeking to get ahead of the president on Cuba after he took unilateral action against Venezuela and