US Democratic senator Barbara Mikulski has publically supported the nuclear deal between Iran and the P5+1 group of world powers.

She is the 34^th senator to back the deal, meaning President Barack Obama now has enough support to override any votes against it.

“No deal is perfect, especially one negotiated with the Iranian regime,” said Mikulski in a statement. “I have concluded that this Joint Comprehensive Plan of Action is the best option available to block Iran from having a nuclear bomb.”

This comes after Senators Bob Casey and Chris Coons agreed to support the deal on 1 September.

Republicans, who dominate Congress, plan to vote against the nuclear accord in their house vote in September. The bill will then move to the Senate. But without enough senators voting against the agreement, Obama will be able to override the bill with a veto. This improves the chances of sanctions on Iran being lifted in late 2015 or early 2016.

According to press reports, the White House will continue to lobby Congress and the Senate to avoid a vote against the agreement. An additional six senators supporting the nuclear deal could prevent a vote on the issue in the Senate, by using a filibuster to delay voting.

Obama would not be forced to veto the decision, strengthening the accord in the US.

The nuclear deal was agreed by Iran, the US, UK, France, China, Russia and Germany in Vienna in July. Tehran commits to opening its nuclear programme to inspections from the International Atomic Energy Agency and ending or reducing some aspects that could be used for nuclear weapons.

In return, the US and European countries will lift economic sanctions that have been crippling the Islamic Republic’s economy.