The result is already a stinging blow for the deal’s principal opponents, the Republican leadership, the American Israel Political Affairs Committee lobby group – which spent tens of millions of dollars campaigning against the JCPOA– and the Israeli prime minister, Binyamin Netanyahu, who waded into US politics to an extraordinary degree in an attempt to block it.
...
Democrats are now trying to reach 41 votes, enough to block the disapproval vote in the Senate by filibuster, and spare Obama from having to spend political capital on a veto.
     -The Guardian.

Mikulski's support leaves 10 undecided Senate Democrats.-Reuters.

From those 10 the Obamas hope to get 7 which would mean Senate approval of the deal, not just the failure of the Israel Lobby's rejection effort. Maybe I shouldn't have added that. For foreign readers that is confusing. The Iran deal is going to go through regardless, Senator Mikulski's support today guarantees that it can't be rejected by the Senate. Forty-one votes, thirty-four today with Mikulski, seven more needed, would mean that the Senate as a whole approved it, like, said "Good job!" It would mean that a future more Republican Senate with a future Republican president would be less able to undo the deal.