DES MOINES, Iowa (AP) — An Iowa historian who crisscrosses the state on a bus converted into a museum is pursuing an independent bid for U.S. Senate, arguing his nonpartisan approach offers a needed alternative to longtime Sen. Chuck Grassley.

More attention has been focused on four Democrats seeking the nomination to face Grassley, who has spent 36 years in the Senate. But Michael Luick-Thrams, a 53-year-old Mason City resident, says he’s the right person to bring new ideas to Washington that will help Iowa.

Luick-Thrams, who grew up on his family’s farm in Iowa and received his Ph.D. in modern European history in Berlin, says he’s focused on invigorating Iowa’s rural areas, which have seen decades of declining population. Supporters say they admire his ability to look at issues without being blinded by party ideology.