Why would Russia and China agree to such a package? And why would, say, the United Nations agree to a move that would push the Iranians to dare the international community to confront it militarily over a global economic chokepoint? The smart people quoted in Sanger's piece make the case for the sanctions by saying that the Iranian regime is more vulnerable to sanctions now, after the theft of the June 12 elections exposed popular anger and antipathy toward it, but not how to make those sanctions feasible.
Neither Russia nor China provide gasoline to Iran. The major companies that do so are European (Vitol and Trafigura) and Indian (Reliance). If you want a UN Security Council resolution ordering them to stop, you need Moscow and Beijing's support in New York. But if the U.S. and other partners can persuade those companies to get out of the trade through other means -- whether through quiet diplomacy with their governments (the ideal) or by threatening sanctions that would forbid them from doing business in the U.S. (less ideal), you can bypass the UNSC.
Now, you aren't going to get 100 percent effective sanctions -- but depending on how effectively we pursue this, we could do better or worse; a lot depends on the implementation. Moreover, even if we do really well on the implementation, it still isn't clear whether -- as Sanger captures at the end of his piece -- it would be enough to convince this Iranian regime from dropping its nuclear ambitions. Ackerman isn't wrong to be skeptical (even if he is skeptical for the wrong reasons); this isn't a magic bullet and it will be tough to fire, but it's also best ammo we've got right now, which is why the Obama administration -- no instinctive ally of Joe Lieberman on Iran -- is coming around to supporting this approach.