From Wiktionary, the free dictionary
From counter- + challenge.
counterchallenge (plural counterchallenges)
- A challenge made in response to another challenge.
2007 April 23, Jonathan P. Hicks, “With Only Days to Stump, 3 Seek Brooklyn Council Seat”, in New York Times[1]:For more than a week, the campaign seemed to be at a standstill while various courts sorted out challenges and counterchallenges.