Ruths, I admire your optimism.
The President actually didn't vote on the CPSIA; he and McCain were on the campaign trail at the time. However, one of his *promises* has been lead-free toys. I don't think he would see much political capital in weakening that stance (WE all know that changes wouldn't compromise safety, but that's how it could be spun).
You may be correct in that he (and those who voted for it) didn't understand the ramifications of the Act. However, those consequences have been brought to light and nothing substantive and lasting have yet been done to fix it. This is in the hands of Congress; the Executive branch can do little.
While he has mentioned the importance of small businesses, little he (and the last and current Congress) has done shows any real support for it, opting instead to grow the government and its regulations, grow the government's debt, and reward the big unions.
Cynicism aside, it's always worth a shot. Perhaps one letter will get through (do we know who picks them and how?) and it may make a difference.