Despite it being a Sunday, on 19 July the US State Department sent a copy of the agreement on the Iranian nuclear program to the US Congress for approval, thereby launching another phase in the political confrontation concerning this issue.
President Obama has obviously chosen Iran as the foreign policy issue in respect of which he would like to secure his “place in history”. The issue having become a matter of personal prestige, President Obama will make every effort to put an agreement with Iran into place.
For their part, Republicans lawmakers will make every effort to disrupt the ratification of the agreement in order to strike at Obama's personal prestige and the prestige of the Democratic Party as a whole. Clearly, the forthcoming US presidential election further exacerbates the confrontation.
Early 2015 witnessed the first round of confrontation over the Iran agreement, in which Republicans will be remembered for resorting to a very unusual political strategy to undermine the position of the Obama administration.
The first such step was the invitation of Israeli Prime Minister Benjamin Netanyahu, known for his sharp rejection of the very fact of negotiations between the US and Iran and his tense relations with President Obama, to address the US Congress. This was a demonstrative violation of foreign policy practice by which an address by a foreign leader to legislators only ever occurs with the consent of, and in coordination with, the executive branch.
On 3 March 2015 the Israeli Prime Minister addressed a joint sitting of the upper and lower houses of the US Congress and subjected the policies of the current US administration towards Iran to the harshest criticism. A week later the Republicans showed themselves capable of even more extraordinary action. Iran's leadership was sent a collective letter signed by 47 Republican senators. In that letter the senators stated that should the proposed agreement in relation to Iran’s nuclear program be achieved, it would be an executive agreement with the current US president, whose term expires in January 2017. Thus, according to the Republicans, "the next president could revoke such an executive agreement with the stroke of a pen and future Congresses could modify the terms of the agreement at any time" after 2017. The letter was written in an openly scornful tone towards Iran.
The letter is an unprecedented step in the history not only of the USA but also other countries. Such a frank attempt to compromise the international prestige of their own Head of State is tantamount to undermining the credibility of the whole country, and probably has no parallel among developed nations in recent decades. This seems to indicate that the internal political confrontation in the United States, which has previously been characterized by public aggressiveness and deliberate stiffness between opponents, has surpassed the ordinary and acquired features of bitterness, not unlike the bitterness that occurs during war.
That stage of the confrontation resulted in the adoption of a law designed to establish a special framework for the ratification of the Iran agreement in the US Congress. The bill was passed in early May 2015. Whilst his opponents are casting doubt on the constitutionality of the law and contending it sooner benefits President Obama, supporters of the Iran agreement claim the President signed the bill into law reluctantly. Now that, contrary to many expectations, an agreement has been reached with Iran, the law will be implemented.
It should be noted that, from a legal point of view, the specially developed procedure for the ratification of the "Iran Deal” really gives Barack Obama the chance to ratify the agreement in spite of opposition from the Republican majority in both houses of Congress (Republicans have 54 of 100 senators in the upper house and 247 of 435 in the lower house). According to the law, the two houses of Congress have until 17 September 2015 to adopt a common resolution expressing agreement or disagreement with the Iran nuclear deal. For his part, President Obama will have the right to veto the resolution, which, of course, will only happen if the resolution is negative.
With Congress on vacation in August, the main confrontation in relation to the resolution will likely unfold in September. However, you can safely assume that Congress will refuse to ratify the agreement with Iran. Therefore, the issue will become whether or not the Republicans in Congress will be able to rally a two-thirds majority (and in so doing win over a fairly large number of Democrats) in order to overcome a presidential veto.
Most probably, the Democrats will be able to close ranks so as not to give the Republicans a victory. In this situation, there is more at stake than the personal prestige of Barack Obama seeking to justify the Nobel Peace Prize bestowed upon him in anticipation several years ago. At stake is the prestige and internal cohesion of the Democratic Party going into an election campaign. If the Republicans manage to derail the agreement with Iran, they can be expected to use it as a "trump card" as the election campaign rolls on.
Winning this round of political confrontation is important to both parties. Given the unprecedented steps taken at earlier stages of this confrontation, we can expect to witness vivid political performances in August – September.
 Christopher Hull. Nuke the Deal: The president ran a U.N. end-run around Congress, now the legislature must reassert itself. U.S. News & World Report, July 22, 2015. URL:http://www.usnews.com/opinion/blogs/world-report/2015/07/22/how-congress-can-still-kill-obamas-iran-nuclear-deal
 Patricia Zengerle, Matt Spetalnick. Kerry: critics of Iran deal spinning ‘fantasy,’ urges approval. Reuters, July 23, 2015