OMAHA, Neb. (AP) — Polls have closed across Nebraska, where the fate of the state’s “blue dot” — a small, but significant factor in presidential politics — took center stage Tuesday as Democrats selected a congressional nominee in the state’s high-profile 2nd District. State Sen. John Cavanaugh and political activist Denise Powell were seen as the top contenders in the Democratic primary as their party looks to the Omaha-area district, where Republican U.S. Rep. Don Bacon is retiring, as one of its top targets in the November general election. The winner will face Republican Brinkner Harding, who ran unopposed in the GOP primary. The Omaha City Council member is endorsed by President Donald Trump. The district draws national attention because Nebraska is one of just two states that splits its electoral votes in presidential elections. The 2nd District has gone to Democratic presidential candidates three out of five times since 2008 — a “blue dot” in an otherwise sea of red.…