Scott Brown wrote on Facebook that O had something in the works, the White House and Harry Reid’s office quickly denied it, and now CNN’s citing sources on both sides who say, yep, there’s a new offer coming.

The tedium-to-suspense ratio of this clusterfark is now approaching that of a “Scooby Doo” episode. And not a good episode, either. One with Scrappy.

A Republican senator said Obama told Senate Minority Leader Mitch McConnell, R-Kentucky, that the president’s plan would arrive on Thursday, and a Senate Democratic leadership member also said that was the approach being taken. Both sources spoke on condition of not being identified further.

The move would answer McConnell’s call for the president or Senate Democrats to make the first move in the political standoff over how to prevent or soften automatic tax hikes and spending cuts of the fiscal cliff set to take effect in the new year — just five days away…

Last Friday, Obama proposed a scaled-back agreement that included his call for extending tax cuts on households with incomes under $250,000, as well as an extension of unemployment insurance.

However, there were no immediate details available on the exact components of the measure that the sources said was headed to Congress on Thursday.

If there’s an offer in the works — and that’s a big if — why would the White House play it close to the vest? That’s the sort of thing you do when you’re serious about negotiations and want to give the other side time to huddle without having to deal with public pressure. There’s no reason for O to be serious about this until next month. Matt Yglesias is unfortunately right that his hand will get stronger, not weaker, once we go over the cliff:

Conrad wants to split the difference between the President’s last offer and Boehner’s last offer. Then once something like that difference-splitting bill passes the Senate, Boehner gets to take it up as the new baseline for negotiations and pull the ultimate resolution even further to the right.

But that’s exactly why Obama would be foolish to take any such thing seriously. Starting in the New Year, the Senate gets more liberal. The House also gets more liberal. And the policy baseline also gets more liberal. The White House isn’t going to pull the plug on negotiations, but unless Boehner comes back to the table with something new to say they have no incentive to further weakn their hand.

Why would O quietly put a credible offer on the table now when he can do a big, showy “tax hikes on everyone who makes more than $250K” take-it-or-leave it ultimatum, wait a week while the media goes to work on how this is all the GOP’s fault, and then come back to the table with even more Democrats in the Senate and the House? And remember, Boehner’s Speakership is on the line on January 3; if O’s plan insists on a relatively low bar for new tax hikes (i.e. $250,000) and Boehner brings it to the floor anyway, that may be the end of his tenure. He needs to be re-elected Speaker first, which means we’re headed over the cliff — unless Obama’s “scaled-back” plan raises the tax-hike bar enough ($500,000? $600,000) to make it kinda sorta acceptable to Boehner and centrist House Republicans. But then you get into a new issue: How far can the bar rise before liberals in the House start to walk away? Getting 30 Republicans to vote yes on a bill that raises taxes on earners over $600,000 isn’t inconceivable, but getting the entire Democratic caucus to vote yes with them might be. The tax-hike “sweet spot” here is narrow; see Nate Silver’s graph today to understand why. How hard is Obama planning to twist Democrats’ arms to get them to back a plan he has no real incentive to offer in the first place?

Then again, Conn Carroll makes a good case that there are enough RINOs in the Senate to pass virtually anything:

Just this Sunday, Politico reported that Sen. Johnny Isakson, R-Ga., has gone on record in favor of a bill that would extend tax rates for incomes below $250,000. “If we get down to the end of this year and the only choice we have is to save taxes going up on the middle class, then I would support that,” Isakson said. And Sen. John Cornyn, R-Texas, committed to a similar policy Friday. “One of the beauties of that bill is it wouldn’t require a vote to raise anybody’s taxes, and I think that is a major advantage,” Cornyn said of a bill that would prevent middle class tax hikes.

That’s two Republican Senate votes Obama’s fall-back plan right there. Now Obama only needs five.

Maine’s Sens. Olympia Snowe and Susan Collins are gimmees. Now Obama only needs three.

Sen. Lisa Murkowski, R-Alaska, is always easily bought and Sen. Scott Brown, R-Mass., will be desperate to vote with Obama while running for a special election in a blue state. That is two more votes right there. Now Obama only needs one.

That last vote will be cast by Dick Lugar, of course. That makes 60 in the Senate, although it’s an open question whether they need even that many. McConnell hasn’t said yet whether O’s plan will be filibustered; Rand Paul, for one, has called on the GOP to let Democrats pass whatever tax hikes they want with Republicans voting “present” to keep their fingerprints off of the results. Assuming it does pass with a low-ish income bar for new taxes, that’ll bring most (or all) of the House’s Democrats onboard. The only mystery then will be whether Boehner’s prepared to hold out, a la Yglesias’s prediction, and demand an entirely new bill with a higher bar or whether he’ll say “to hell with it” and let centrist Republicans vote to push it through. My money’s on the latter — but not before January 3.

Exit question: What sort of guarantees will Boehner need to make to the GOP caucus about the fiscal cliff to survive the Speaker vote? House conservatives won’t vote for him if they expect him to cave on Obama’s tax-hike plan the day after. He’ll have to give them some sort of assurance to make it through.

Update: Double hmmmm:

House Republican leaders are bringing the House back into session on Sunday, lawmakers were told in a Thursday conference call…

“We are waiting on the Senate,” [Boehner] told lawmakers on a call restricted to the 241 lawmakers in the House Republican Conference.

My gut reaction when I saw that was that maybe there really is a scaled-back Obama plan after all and Boehner’s getting ready in case he needs to vote on it. But maybe not. One of the big GOP worries in all this is that they’ll take the blame if we head off the cliff; if the House isn’t even in session when it happens, it’ll make the media’s inevitable “Republicans aren’t serious” narrative that much easier for them. Best to have all hands on deck and prepared to act even if nothing happens.