Stock index futures gave up earlier gains on Thursday as questions remained about the nature of a European deal to help Greece deal with its debt crisis.

An European Union source said the obstacle to a more detailed agreement on Greece support now is a lack of German junior coalition partner consent.

S&P 500 futures fell 1.5 points and were below fair value, a formula that evaluates pricing by taking into account interest rates, dividends and time to expiration on the contract. Dow Jones industrial average futures lost 7 points, and Nasdaq 100 futures slipped 1.5 points.

(Reporting by Leah Schnurr)