LITTLE ROCK — A group is asking Arkansas’ highest court to disqualify a ballot measure that would legalize four casinos in the state. Ensuring Arkansas’ Future filed a lawsuit Monday with the state Supreme Court challenging the proposed constitutional amendment, which election officials approved to appear on the November ballot. The proposal would legalize casinos at a Hot Springs horse track and a West Memphis dog track that already have video poker and other forms of electronic gambling. It would also allow casinos in Jefferson and Pope counties. Ensuring Arkansas’ Future is a group that was formed to oppose and campaign against the casino measure. The lawsuit claims the text of the proposed amendment is unclear and misleading on several issues.