.By Mary Ellen McEntire and Daniela Altimari

We’re still holding on to summer here at At The Races, but Congress is back in session and the post-Labor Day campaign rush is here.

While the Senate fields in several key states have been clear for months, other races are still taking shape. As lawmakers returned to Washington on Tuesday, Iowa Sen. Joni Ernst confirmed earlier reports that she wouldn’t run for a third term next year. A matter of hours after her announcement, fellow Republican Ashley Hinson, who represents the state’s 1st District, threw her hat in the ring for the newly open seat and rolled out a slew of endorsements.

In Maine, brewer Dan Kleban is the latest Democratic entrant into the Senate race, joining former Hill aide Jordan Wood and oysterman Graham Platner in seeki

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