The FBI is investigating whether the Democrats secretly recruited an Alaska Senate candidate called Dan Sullivan to stand against the Republican incumbent with the same name.
The US security service on Friday sent an agent to the remote Alaska fishing village of Petersburg, where the midterms challenger, Daniel J Sullivan Jr, lives.
Democrats are accused of planting Mr Sullivan to stand as an independent candidate against Dan S Sullivan, Alaska's current Republican senator, as part of a secret plot to confuse voters in the midterms.
