WASHINGTON (JTA) — An AIPAC-backed letter urging President Obama to exert greater pressure on Iran to end its suspected nuclear weapons program and to seek avenues to diplomatic resolution garnered the signatures of 76 senators.

The letter, which was initiated by Sen. Robert Menendez (D-N.J.), the chairman of the Senate Foreign Relations Committee, outlines what it says are the four “necessary strategic elements” to dealing with Iran.

“An explicit and continuing message that we will not allow Iran to acquire a nuclear weapons capability; a sincere demonstration of openness to negotiations; the maintenance and toughening of sanctions; and a convincing threat of the use of force that Iran will believe,” the letter said. “We must be prepared to act, and Iran must see that we are prepared.”

The letter notes overtures by new Iranian President Hassan Rohani to make more transparent a nuclear program Iran insists is peaceful, but also demands that Iran agree to remove 20 percent enriched uranium, which Rohani has said is a non-starter.

The American Israel Public Affairs Committee lobbied for the letter, which drew signatures from 76 of 100 senators.

The letter closed Aug. 2 and is due to be sent on Monday.

Another letter circulating, initiated by Sen. Dianne Feinstein (D-Calif.), was more conciliatory, urging Obama to test Rohani’s offer to deal.

There was no word yet as to how many signatures that letter, backed by J Street and Americans for Peace Now, had garnered by week’s end.