Why it is unrealistic to send astronauts back to the moon now?

A panel of experts appointed by the White House has warned that current plans to send astronauts back to the moon in preparation for manned missions to Mars are just not viable.One of the panel members Li Ruoqiao says the space agency NASA hasn’t been given enough funds to realize the plans.
    "That is when the visions for space aspirations were first announced in 2004 mere was expectation of a certain budget level of the next several years. In fact over the last five years those numbers are nothing realized. So because of that we are in a pickle that we are in now."
    The experts say the current budget of the space agency NASA would need to be increased by billions of dollars.Without the extra money, the experts say, NASA would have to work with private companies now trying to embark on commercial space flights.