It's not Leahy's first rodeo. Perhaps we should assume his intent is to kill the bill. So as to keep it as a campaign issue? To avoid getting blamed for something so unpopular? Others more Washington-savvy than I would know.
There's no reason why Democrats would want to kill this bill.
If it does die, they're going to revive it-just like the DREAM Act-but there's no way they'll pass up a chance to enfranchise millions of future statist, dependent Democrats.