He wasn’t the Democratic Party’s first choice for Akron mayor.He wasn’t even the second.But when the top leadership in Akron imploded, Summit County Clerk of Courts Dan Horrigan suddenly emerged as the top mayoral pick of the power structure in Akron.Prominent politicians lined up behind him, including Summit County Council President Ilene Shapiro and Akron Planning Director Marco Sommerville, his campaign co-chairs who mulled their own mayoral bids.