There are deep concerns in the Senate and in the White House that GOP presidential candidate John McCain, eager to break from President Bush, will vote against the $700 billion Wall Street bailout in a bid to show his maverick status. Senate leadership aides tell me that it's a "very real concern," though in the end they expect him to come on board and follow the directions of the Senate Republican bosses. "We don't want to vote for this thing and then McCain comes in and votes no, leaving us holding the bag," said a Republican aide. It's of such concern that now even Democrats like Senate Majority Leader Harry Reid are pushing McCain to spell out his plans. The reason: Without solid GOP support, the plan will fail, and many Republicans are looking to McCain to signal how they should vote. "We're going to keep hammering McCain on where he stands," said a very senior Democratic leadership aide. He's not the only one calling for McCain to speak up: Former House Speaker Newt Gingrich wants McCain to say "No" to Bush.