This won't help fill the gaps on my ballot. It's the thirtieth Oz novel, in the series started long long before by L. Frank Baum, but the first by John R. Neill. It starts with a heroine who herself takes her name from a racist legend of the New Jersey/Pennsylvania border, having an encounter with a leprechaun who is as Oirish as they come. The happy ending of the book - I am not making this up - comes when the Wizard of Oz surgically removes any trace of ambition from the heroine, so that she can be a modest and pleasant girl. There is an election, which is determined by assigning voters to each candidate randomly and adding up their total weight. (Oz experts claim that this bit was not written by Neill. It's one of the better bits of the book.)
By my count it just struggles across the 40,000 word threshold to count as a novel. But I hope that next year's Hugo administrators won't need to make that judgement.