Does He Have a Raffle License?

From the Obama campaign:

Backstage with Barack

If you make a donation in any amount before midnight on July 31st, you could be selected to travel to Denver for the last two days of the convention -- including the huge event at the open-air stadium on the final night.

Ten supporters from all over the country will be selected to go Backstage with Barack.

We'll provide airfare, accommodations, and two days of convention activities for each supporter and their guest -- including a private meeting with Barack before his historic speech.

Is it legal to require someone to pay to enter a contest? Do the words "no purchase necessary" ring a bell?

Did the campaign get a nation-wide license for this "raffle"?

Barry states:

There are no strings attached.

Except for the fact you have to give him money. -- No strings, though.