Complex sentence: Kovach was chosen as the Republican candidate to run against Democrat County Councilman Tim Sheldon, and won 57% of the vote, making him the first Republican to win this office in 23 years.
Split into simpler sentences: Kovach was chosen as the Republican candidate for this position, running against county councilman Tim Sheldon, a Democrat. He won the election with 57% of the vote, making him the first member of his party to win this office in 23 years.