AMBIGUITY reigns in the twisting, turning dramatic series that is the fiscal-cliff negotiations. On Monday, it appeared Barack Obama and John Boehner were close to a deal. Liberals were angered by some of the apparent concessions: raising the income threshold at which tax increases kick in from $250,000 to $400,000 per year ("muddying the message", some cried), switching to chained CPI for social-security cost-of-living increases, accepting a two-year waiver on the debt ceiling rather than declaring it permanently off-limits for negotiation. But Mr Boehner blew that apart on Tuesday, rejecting the White House compromise and announcing a retreat to "Plan B": having the Republican House pass a bill that hikes taxes only for income over $1m per year, with no other spending measures or tax compromises. Had Republicans smelled weakness in the Democratic position? Or was Mr Boehner bolting because he was unable to get his tea-party wing online for any deal? Then, on Wednesday, the game shifted further, as the conservative Heritage Foundation and Club for Growth both attacked "Plan B" as a tax-hiking sellout and warned Republican lawmakers not to vote for it. Was even Mr Boehner's symbolic conservative gesture of defiance too centrist? Were the Republicans falling apart, as John Chait argued? On the other hand, Grover Norquist's Americans for Tax Reform (ATR), keeper of The Pledge, declared it would issue an indulgence to any lawmakers who have signed the no-tax-hikes-ever pledge but vote for Plan B, on the casuistic argument that Plan B does not technically raise taxes on income above $1m per year, but prevents them from being raised on income below. Late in the day, Mr Boehner gave an exceptionally terse 51-second press conference, announcing the House will vote on Plan B. As that vote approaches today, the world watches with bated breath: will Mr Boehner hold his party together, prevent more than 24 representatives from defecting, and get the Republican House to pass a bill on strict party lines that (with apologies to the Jesuits at ATR) everyone in the world understands as a tax hike on millionaires? If he does, the bill is obviously going nowhere in the Democratic-controlled Senate. Will its passage lead to a new round of negotiations over a real compromise? Or will both sides allow the country to sail over the fiscal cliff, with Mr Obama hoping the public continues to blame Republicans for the failure of negotiations, while Mr Boehner hopes that the passage of Plan B allows him to blame it on Mr Obama? The answer to that last question has a lot to do with the incentives facing Mr Obama at this point. It's not simply that he may get a better deal on taxes and spending cuts, from a Democratic perspective, if he allows the fiscal cliff to kick in on January 1st. It's also that letting the fiscal cliff kick in may better serve his other main incentive: dividing and weakening the Republican Party. Mr Boehner's Plan B is an attempt to defray blame for the fiscal cliff onto Democrats, but if the country actually goes over the cliff, Plan B is unlikely to shield Republicans. Pressure from business groups and from taxpayers to reach a compromise deal before the economy suffers serious damage will become immense. Polls are consistently showing Americans more likely to blame Republicans than Democrats if negotiations fail. The president's initial $250,000 tax-hike cutoff still enjoys majority popular support; his secondary $400,000 cutoff is already a substantial compromise. The GOP is suffering tremendous political stress while the standoff continues, and that stress will become unbearable once tax hikes and defence sequesters kick in. Mr Boehner will have to come up with a Republican position that Democrats can accept, and it is likely to be very close to the offer Mr Obama put forth on Monday.

A vote over such a compromise deal would tear the GOP's congressional faction apart. However many Republicans defect on today's vote over Plan B (The Hill's count currently has 11 saying they'll vote no and 25 more no-comments and undecideds), a multiple of that number would refuse to vote for a real compromise with the Democrats. Democrats could achieve a fiscal-cliff deal by winning the votes of a couple of dozen moderate Republicans, but such a move would be electoral suicide for any Republican who tried it. Republicans will need to form a large bloc to give themselves cover for a compromise, but the larger the bloc, the more dangerous the division between the party's tea-party and moderate factions will be for its overall future.

Fostering the civil war in the Republican Party is crucial to Mr Obama's chances of getting any part of his agenda passed over the next four years. The top items on that agenda are climate-change legislation, immigration reform, and (suddenly) gun control, along with keeping up some measure of progressive stimulus until the economy is fully recovering. But if the Republican faction in the House stays as united as it has been for the past 18 years, only immigration reform has any chance of passing. If Mr Obama can crack Republican party discipline on taxes, he may be able to press the other items on his agenda as well. Alternatively, he can look forward to elections against a divided, angry GOP in 2014, and hope to go into the last two years of his term with a stronger position in the House.

Republicans have locked themselves into an impossible position on budgeting by simultaneously vowing never to allow taxes hikes, and passing long-term budgets that create a fiscal cliff necessitating tax hikes. It's in Mr Obama's interests to gain Republican cooperation to work out the best possible deal, but if that's not forthcoming, it's also in his interests to use the impossibility of the Republicans' position to weaken them. Back before the elections, Mr Chait wrote a piece distilling the thinking he'd heard from Obama aides on the budget debates. "The term that keeps popping up among Obamans is break," Mr Chait wrote, "as in, 'we have to break the Republicans on taxes.'" That strategy seems to be working out. Either Mr Obama is going to break the Republicans on taxes, or he's going to try to break the Republicans. On taxes.

(Photo credit: AFP)