WICHITA, Kan. (AP) — Newly released campaign finance reports show a late infusion of cash from mostly small donors helped Democrat James Thompson mount his surprisingly close congressional race as emboldened Democrats eye a 2018 rematch in the heavily Republican Kansas district.

The margin of victory for Republican Ron Estes in the Kansas 4th District special election on April 11 slid to only seven percentage points from a 31-point margin in November, when incumbent Mike Pompeo was running before he was appointed Trump's CIA director.

Reports filed late Thursday show that as of May 1 Thompson...