Vice President Joe Biden, left, and San Antonio Mayor Julian Castro share a moment onstage at Iowa Sen. Tom Harkin's Democratic fundraiser earlier this week. (Steve Pope/Getty Images) Vice President Biden, left, with San Antonio Mayor Julian Castro earlier this week. (Steve Pope/Getty Images)

Vice President Biden and U.S. Middle East envoy Martin Indyk will speak at the annual conference of the liberal, pro-Israel lobby group J Street this month. The Sept. 30 appearance signals that the Obama administration will continue to press for a Mideast peace accord even as it grapples with the ongoing crisis in Syria.

The decision by Biden and Indyk to address the Washington-based group, which advocates a two-state solution to resolve the conflict between Israelis and Palestinians, underscores the growing influence of an organization that has clashed on several occasions with the traditional American Jewish lobby. While groups such as the American Israel Public Affairs Committee lobbied lawmakers this month to support a resolution authorizing the use of force against Syria, for example, J Street remained neutral.

In an interview, J Street president Jeremy Ben-Ami said the vice president's presence at the conference "is a very strong signal about the high priority that the administration places on achieving an Israel-Palestinian deal by the end of this term... They clearly understand that in order to achieve that goal they’re doing to have to build what [Secretary of State] John Kerry calls ‘the constituency for peace,’ both in the Jewish community and beyond."

Biden and Indyk's appearance will take place the same day Israeli Prime Minister Benjamin Netanyahu will meet with President Obama at the White House to discuss concerns about Iran, Syria and peace negotiations with the Palestinians.

Biden, who chaired the Senate Foreign Relations Committee before running for higher office, has played a key role in helping shape the administration's Mideast policy. He lobbied both Democrats and Republicans to support the congressional resolution on Syria before the Russian government helped broker a compromise under which Syria has pledged to place its chemical weapons stockpile under international control.

On Tuesday, Biden spokeswoman Kendra Barkoff confirmed the vice president's decision to attend the event but declined to comment further on the matter.

Dennis Ross, a former senior Mideast adviser to President Obama who now serves as the Washington Institute for Near East Policy's counselor, said Biden's appearance shows that the entire administration, not just Kerry, is committed to the peace process.

"J Street has defined that as its most central mission," Ross added.

Rabbi David Saperstein directs the Religious Action Center of Reform Judaism. He said the vice president's decision reflects not only that the administration is heavily invested in the peace process, but the recognition that the America Jewish community will play a critical role in achieving that goal, and "the recognition that J Street is one of the few entities capable of pulling together such a significant section of the Jewish community that is committed to the peace process."

J Street has come under fire from some conservatives for receiving donations from George Soros, a frequent contributor to liberal causes, and for opposing the construction of settlements in the West Bank.

But Saperstein, who shares many policy positions with J Street, though has differed with its leadership on a handful of questions, said the group has begun to influence not only U.S. policy but politics in Israel, as well. That has translated, he said, into "the Israeli government refraining from taking provocative actions" that would impede the peace process.

Biden has reached out to other pro-Israel groups in the past. In March, for example, he spoke to AIPAC in Washington shortly before President Obama visited Israel for the first time while serving in office.