Anticipating a month of heavy lobbying and television advertising by opponents, led by the pro-Israel group Aipac, the president and members of his team are leaning on Democrats to declare their backing for the agreement before they leave Washington to face their constituents.

Mr. Obama, who will decamp to Martha’s Vineyard this weekend for his own two-week vacation, will have limited personal contact with wavering lawmakers, but his team has been instructed to make the president and other senior administration officials available to any skeptic with an unanswered question or concern about the deal. “Anyone who wants a phone call will get one,” one official said, speaking on the condition of anonymity to outline internal strategy.

Officials said that Mr. Obama’s address on Wednesday would be followed by a series of news media interviews that would be shown next week. And the administration plans to dispatch cabinet members, including Energy Secretary Ernest J. Moniz, the nuclear physicist who helped negotiate the accord, to travel the country outlining its provisions. Mr. Moniz will appear on Friday at the Chicago Council on Global Affairs, officials said.

“We are confident that a sizable number of members of Congress will put politics aside and focus on what they believe is in the best interest of the United States and our national security, and if they do, a substantial number of those who follow that path will be supportive of the agreement,” said Josh Earnest, the White House press secretary. “There’s no denying that there is intense political pressure on both sides of this agreement,” he continued, adding that officials were hoping that lawmakers would “focus on the specific terms of the agreement.”