My guess is there wouldn’t be a planned mission just 2 years away if they didn’t already set aside budget to do it. I don’t know the inner workings of how NASA budgets things but I doubt they let upcoming missions ride on the whims of congressional mood.
Discussion
Proves there’s more intelligence within NASA than Congress which is always cowing to the whim of moods. One of these groups is significantly more capable of pulling off an organized plan.