Washington: Two more US Democratic senators said on Tuesday they will support the US-led international nuclear agreement with Iran, while another Republican senator said he will oppose it.

Indiana�s Joe Donnelly and Massachusetts� Ed Markey, both Democrats, announced their support for the deal, which would place new limits on Iran�s nuclear programme while lifting economic sanctions on the country.

Georgia Republican Johnny Isakson said he will vote against the agreement, which almost all Republicans oppose.

Obama is trying to gather 34 votes in the Senate to ensure that lawmakers cannot kill the deal. Twenty-five senators, all Democrats, have said they will support it, meaning Obama needs to lock up nine more votes.

The following describes how votes are likely to play out:

* When Congress returns on September 8 from its long August recess, debate will begin on a Republican-sponsored �resolution of disapproval� against the deal.

* In the Senate, the Republicans must gather 60 votes to move the resolution forward under Senate procedural rules. If they can, they will then need 51 votes to approve the resolution. They have until September 17 to get this done.

* There is no similar procedural barrier in the House. The resolution is expected to easily win approval there.

* If both chambers approve the resolution, it would go to Obama�s desk for review. He has vowed to veto it.

* If he does so, opponents would then probably try to override the veto. This would take a two-thirds majority vote in each chamber. The Senate has 100 members; the House, 435.

* Democrats could block an override in the Senate with 34 votes. So far, 25 senators have committed to voting in favour of the deal; 20 have said they will oppose it.

* In the House, if Republicans voted unanimously to override, they would need to get at least 44 Democrats to do the same.

By Gulf News