What is the current state of the legality of online gambling for U.S.
citizens?

Has it been banned by Congress already? And if not, is there any
pending legislation concerning online gambling?

To be concrete, I wonder about the following question. If I am a U.S.
citizen, can I log onto an online sports book, place a bet on the
Super Bowl, and legally withdraw my potential winnings just as I might
take winnings home from a Las Vegas vacation?

I have addressed the same question to online sports books themselves,
but they simply reply that it is the responsibility of each individual
to determine the legality of their own activities. I would like to to
do so, but I lack the resources to research the finer points of law
about online gambling.

Thank you.