WASHINGTON — A trio of Obama administration officials will stand stalwart behind the Iranian nuclear deal despite deep concern on Capitol Hill that Iran will try to evade nuclear inspectors and use billions from sanctions relief to further destabilize the Middle East.

Members of the Senate Foreign Relations Committee today are to pose tough questions to Secretary of State John Kerry, Energy Secretary Ernest Moniz and Treasury Secretary Jack Lew about the deal that Congress is expected to vote on in September. The three were on Capitol Hill Wednesday for back-to-back classified briefings in the House and the Senate.

A debate is under way between supporters and the opposition, which includes many Jewish groups that point to Iran’s pledge to destroy Israel. Vote counters are eyeing Democrats, especially those who represent large Jewish constituencies and likely will be lobbied hard to oppose the deal at home during the August recess.

Most Democrats — except Sen. Dick Durbin of Illinois who announced his support earlier in the week — came out of the classified briefings saying they were still deciding whether to support the agreement, which Congress has 60 days to review.

“I think the deal is a dramatic improvement over the status quo from day 1 through probably year 10 to 15. Thereafter my questions are about our ability to detect cheating after some of the provisions start to expire,” said Sen. Tim Kaine, D-Va., who sits on the committee.

“I’d be shocked if there’s more than a handful of Republican ‘yes’ votes if there are any at all,” said Sen. Chris Murphy, D-Connecticut. “I think the administration is one-by-one picking off some of the most important lingering questions from Democrats.”