Drawing on their individually distinct backgrounds, the participants collectively emphasized the effects that the deal might have on nuclear proliferation, Iran’s support for global terrorism, and the persistence of the theocratic Iranian regime and its repression of the rights of the Iranian people. The panel discussion is only one in a growing list of meetings and communications aimed at encouraging opposition to the nuclear deal, as well as promoting a more assertive Western strategy toward dealing with Iranian nuclear ambitions and regional influence.

It is fair to say that the vast majority of this advocacy inside the United States is aimed at changing the minds of congressional Democrats, whose votes will be needed to override the presidential veto that would otherwise allow the deal to go into law over the objections of the Republican majority in Congress.

Nearly all congressional Republicans are opposed to the deal, and their opposition will be sufficient to secure a vote of disapproval under the Iran Nuclear Agreement Review Act of 2015. The Daily Signal reported on Monday that Kentucky Republican Senator Rand Paul reiterated in an interview that Congress will reject the Obama administration’s agreement with Iran, adding that the only question is whether it will also override his certain veto.

The answer to this question is not as clear as it appeared in the days immediately following the announcement of the agreement. At the same time that opponents of the deal are vigorously campaigning against it, the Obama administration is finding it necessary to keep up its own campaign, not only to retain Democratic allegiance but to actually secure Democratic votes in the first place.

The Daily Signal reports that the administration recently secured two such votes in the form of Representative Chris Van Hollen and Senator Tom Udall, and the Washington Post pointed out on Monday that Representative Adam Schiff had also decided in favor of the deal. But the Post also notes that Democratic Representative Kathleen Rice had officially come to the opposite conclusion. Meanwhile, the Post reports, the situation is distinctly difficult for Obama, since virtually all of the remaining undecided votes on the Iran nuclear agreement are Democrats.

Notably, these include the third highest ranking Senate Democrat, New York’s Charles Schumer, who responded evasively to pressure from both sides on Monday, according to CNN. Schumer claims that he is still studying the deal and will vote his conscience when the time comes, but he is a prominent target of campaigning, as it is expected that his opposition to the deal might bring additional Democrats along with him.

Schumer previously emphasized that he has broken with his own party in the past and would do so again if he believed it was the right thing to do. But realistically, many outstanding decisions on this topic will be made on the basis of both principles and political considerations. The Washington Post pointed out that both the material and the political fallout from this deal are likely to last for years, making the consequences of an imprudent vote very serious for Democrats who are on the fence.

Schumer has pointedly refused to say whether he has spoken with Israeli Prime Minister Benjamin Netanyahu, a major opponent of the deal and a driving force behind the powerful lobby that sees it as an existential threat to the state of Israel. Fueling this narrative, the New York Post reported on Monday that Iranian Supreme Leader Ali Khamenei recently published a book in Iran that calls for the “annihilation” of Israel and urges a continued threat of violence to drive Jews out of the region.

Meanwhile, critics have been emphasizing recently revealed provisions of the nuclear deal that allow for the removal of sanctions on Iranian individuals and entities associated not only with its nuclear program but also with its regional intrusions and its support for terrorism. Prominent among these is Ahmad Vahidi, the former commander of the Quds Force of the Iranian Revolutionary Guard Corps and a suspect of the 1994 bombing of the Argentine Israel Mutual Association, which killed 85 people.

Primarily on the basis of these sorts of provisions, Robert Morgenthau, in a Reuters blog post, compared the forthcoming congressional vote on the Iran nuclear agreement to its 1986 vote on the Comprehensive Anti-Apartheid Act sanctioning South Africa for its institutionalized racial segregation. Morgenthau suggests that history will judge failure to overturn the nuclear deal about as harshly as it would have judged Congress’ failure to pass that bill.

These sorts of arguments may be having an effect on the American electorate just as well as on some of its representatives. The Washington Post points out that few legislators have arranged to hold town hall-style meetings in order to hear from their constituents regarding how to vote. But ABC reports that if they were to do so, they might find that a majority of people urge them to vote against the deal. The latest Quinnipiac University poll on the topic finds that Americans are opposed to the deal by a margin of two to one, with a majority believing that the passage of the agreement would ultimately make the world a more dangerous place.

However, even some prominent critics believe that the deal can be salvaged if Western powers pursue more assertive policies toward Iran following the implementation of the deal. Olli Heinonen took this position in his comments to the Washington Press Club on Monday when he declared that the deal would provide more time for diplomacy to work if the West has a plan. But he quickly added that at present no such plan seems to be in place.

In a blog post for the Wall Street Journal on Monday, Stephen Sestanovich presented one potential plan that build upon acceptance of the current deal. He urged the Obama administration to declare outright that it will take whatever action is necessary – up to and including military action – if Iran pushes the limits of the nuclear agreement by pursuing levels and quantities of nuclear enrichment that reduce its breakout period for a nuclear weapon.

Heinonen said on Monday that the deal as written appears to succeed in pushing Iran’s breakout period from two or three months to one year. But he added that this one year breakout would almost certainly degrade a few years after implementation of the deal, as Iran purchases advanced equipment and creates obstacles to inspection.

Sestanovich also suggested that President Obama should be willing to renounce the agreement if Iran makes this necessary. But other critics appear less willing to wait. In an editorial for the New York Times, former US ambassador to the UN John Bolton once again criticized Obama for relying on violable verification and “snapback” of economic sanctions to enforce Iran’s compliance, rather than retaining a credible military option.

The degree of interest in such an option varies from one critic to another, but virtually all opponents of the nuclear deal cite the need for some form of enhanced pressure on the Iranian regime in order to force compliance and elicit more serious concessions on the nuclear file and related issues.