The letter was sent to Congress on Monday by former senators and House members, including both Democrats and Republicans, such as senators Carl Levin and Richard Lugar.

The former lawmakers warned that rejecting the Iran nuclear agreement, known as the Joint Comprehensive Plan of Action, will increase the likelihood of a military confrontation.

"We believe that the Joint Comprehensive Plan of Action that the United States and our P5+1 partners negotiated with the government of Iran is the most viable means to prevent Iran from acquiring a nuclear weapon and protect the security of the United States, Israel and other allies," they wrote.

"We are writing to you as former Members of Congress to urge your support of this historic agreement,” the letter read.

This is the latest petition that calls on American lawmakers to support the nuclear deal.

Letters to Congress have already come from rabbis, nuclear scientists, arms-control and nuclear nonproliferation experts and retired generals who support the deal.

US President Barack Obama says he is confident that the nuclear accord will go forward despite opposition from congressional Republicans.

Political analysts do not believe there will be enough votes to override Obama’s veto of a congressional resolution against the deal.

"Supporting the agreement does not come without risks.  But these risks must be considered in the context of the grave risks that would be incurred if you were to reject it," the former lawmakers said.

"These include the unraveling of international sanctions, the suspension of international inspections and an Iranian government that is unconstrained in developing its nuclear program. They also include the increased likelihood of a military confrontation," they added.

The United States, Israel, and some of their allies accuse Iran of pursuing military objectives in its nuclear program, Press TV reported.