WASHINGTON (AP) — President Barack Obama spearheads the latest push to garner support for the Iran nuclear deal with a speech at American University while administration officials work to persuade skeptical lawmakers on Capitol Hill.

Wendy Sherman, undersecretary of state for public affairs, and Adam Szubin, acting undersecretary of the Treasury for terrorism and financial crimes, are to appear at a Wednesday morning hearing of the Senate Banking Committee. In another part of the district, Obama will be defending the deal on the 52nd anniversary of the nuclear test ban treaty — the landmark agreement signed by President John F. Kennedy and leaders from the Soviet Union and Britain.

Also on Wednesday, Yukiya Amano, director general of the International Atomic Energy Agency, is briefing members of the Senate Foreign Relations Committee. Sherman, Szubin and Energy Secretary Ernest Moniz will brief senators in a closed-door session.

Congress' vote on the international accord to curb Iran's nuclear program in exchange for billions of dollars in economic sanctions relief is one of the most crucial national security decisions lawmakers will make since the 2002 vote to authorize the invasion of Iraq.

A news guide to the pact:

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LOBBYING FRENZY

Lobbying for votes is intense and many Jewish members of Congress are being targeted because Israeli Prime Minister Benjamin Netanyahu has denounced the deal with Iran, which has threatened to destroy the Jewish state.

A group backed by the pro-Israel group American Israel Public Affairs Committee launched a multimillion-dollar ad campaign criticizing the deal.

Another pro-Israel group, J Street, on Tuesday launched a television ad campaign as part of its $5 million effort to rally support for the deal.

Peace groups and scores of other organizations are weighing in as well.

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REVIEW PERIOD

Congress is engaged in a 60-day review of the historic deal and has until Sept. 17 to vote on a resolution either approving or disapproving the pact.

Six weeks from a September vote, House Republicans formally introduced a resolution of disapproval on Tuesday. The GOP has said it has the 218 votes for the resolution.

Congress returns from its August break on Sept. 8, and the Republican-led House and Senate are expected to vote for a resolution of disapproval and send it to Obama.

The president will have 12 days to veto the measure, as he has promised. The House and Senate then would have 10 days to vote on overriding a veto.

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HOW TO SUSTAIN A VETO

Only one chamber of Congress is needed to sustain a veto. In the 434-member House, that would be one-third plus one of those voting. In the 100-member Senate, one-third plus one of those voting.

The White House expressed confidence that Obama's veto would be sustained in the House though the administration was still pressing its case with lawmakers.

While Obama has picked up the support of three Democratic senators — Barbara Boxer of California, Bill Nelson of Florida and Tim Kaine of Virginia — he lost the backing of three of the most prominent Jewish Democrats in the House: Reps. Steve Israel and Nita Lowey, both of New York, and Ted Deutch of Florida.