SELECT candidates FROM table_2668374_10 WHERE incumbent = "Samuel Riker"
CREATE TABLE table_2668374_10 (candidates VARCHAR, incumbent VARCHAR)
ใครคือผู้สมัครชิงตำแหน่งเมื่อ Samuel Riker ดำรงตำแหน่ง?
Who were the running candidates when Samuel Riker was the incumbent?