The Law-Makers and Large Numbers

From forbes.com:

In fact, some of the most basic details, including the $700 billion figure Treasury would use to buy up bad debt, are fuzzy.

"It's not based on any particular data point," a Treasury spokeswoman told Forbes.com Tuesday. "We just wanted to choose a really large number."

Paulson admits that they're unlikely to spend more than $50 billion a month. Why can't we just give Treasury the authority to spend, oh, $100 billion and then sort this out after the election?