Holy election tie-in: Erik Ekstein, who's developing +aRT, an 88-unit Chelsea condo that just began sales last week, says he's including an "Obama Contingency Clause" in all contracts that go into effect between now and Election Day. If Obama wins, the contract goes through, but if John McCain prevails, buyers can back out — and presumably move to Canada — "with no questions asked." (He says he came up with the idea after talking to potential buyers, who seemed to be holding off until the election.) Ekstein, a big supporter of the Democratic candidate, says he's not worried he'll lose business. "It's a very narrow window, and we're fairly confident he'll win," he says.