WASHINGTON (JTA) — Competing letters on Iran are circulating in the U.S. Senate, one urging President Obama to increase pressure to force Iran to suspend its suspected nuclear weapons program and another urging him to engage with an offer to talk by Iran’s president-elect.

Pro-Israel backing is split between each of the letters seeking senators’ signatures this week, with Americans for Peace Now and J Street backing the more conciliatory letter and the American Israel Public Affairs Committee backing the letter that urges intensified sanctions.

“We believe the U.S. should reinvigorate diplomatic efforts to determine whether Dr. Rohani is truly willing to engage the international community,” says the letter initiated by Sen. Dianne Feinstein (D-Calif.).

Hassan Rohani, who will be inaugurated this weekend, rejects calls to reduce Iran’s uranium enrichment, but has also said that he is ready to make more transparent Iran’s nuclear program, which that country’s leaders insist is peaceful.

Diplomacy “is the only way to reach a verifiable agreement, including limits on Iran’s enrichment and other sensitive nuclear activities and greater cooperation with the [International Atomic Energy Agency], that ensures that Iran will not develop nuclear weapons,” says the letter authored by Feinstein, who chairs the Senate’s Intelligence Committee.

The letter demanding greater pressure was initiated by six senators, led by the chairman of the Senate Foreign Relations Committee, Sen. Robert Menendez (D-N.J.), and including the chairman of Middle East subcommittee, Sen. Tim Kaine (D-Va.) and Sen. Lindsey Graham (R-S.C.).

“We believe there are four strategic elements necessary to achieve resolution of this issue,” says the letter, which is backed by AIPAC. “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. We must be prepared to act, and Iran must see that we are prepared.”

The letters come on the heels of an overwhelming 400-20 vote in the U.S. House of Representatives this week to intensify sanctions as well as a letter last week from a bipartisan slate of 131 House members urging Obama to take up Rohani on his offer to talk.

Notably, there is some thematic overlap between the Feinstein and Menendez letters: Feinstein’s says sanctions should be sustained until Iran takes “proportionate steps” to show that it is not manufacturing weapons. The Menendez letter notes Rohani’s expressed willingness to make the nuclear program more transparent.

Israeli Prime Minister Benjamin Netanyahu has said he does not take seriously Rohani’s offer, calling him a “sheep in wolf’s clothing.”