A hollow victory in Washington

The votes have been tallied. At least 34 US Senators will support the Iran nuclear deal and back President Barack Obama's anticipated veto of a resolution that disapproves of the agreement. To put it simply, those in Congress who oppose the nuclear deal have been defeated - for now.

There's a good chance that Congress will pass the disapproval resolution. After all, both the House of Representatives and the Senate are controlled by the Republican Party, which is bitterly opposed to the nuclear agreement. At least two leading Democrats, Senators Robert Menendez and Charles Schumer, are also opposed. They have until September 17 to vote on the resolution.

Should the disapproval resolution pass, President Obama would issue a veto. In order to override a presidential veto, opponents of the deal would then need two-thirds support in the House and the Senate. Senator Barbara Mikulski's decision on Wednesday to support the nuclear agreement ensures that opponents will not have the 67 votes needed in the Senate to override the president's veto.

According to Jeffrey Peake, many opponents of the Iran nuclear deal knew from the beginning that they would probably lose the showdown with the president. But the impending vote gives them the opportunity to state their opposition to the historic agreement on the record.

"They knew the writing was on the wall," Peake, an expert on the role of Congress in American diplomacy, told DW. "It was pretty to clear to everyone involved that the veto would be sustained."

"It allows them a vote where they can go home to their constituents and say, 'I voted to oppose this deal. It's on the record,'" Peake said. "They have capitulated basically, but it's so convoluted and complicated that most observers and constituents aren't going to see that."

US sanctions

The process always weighed heavily in President Obama's favor. He needed to rally just one-third of the Senate to guarantee the resolution's ultimate demise. But he did run a political risk, however small.

Americans are deeply divided over the Iran deal, and supporters of Israel have been lobbying hard against it. Republicans hoped to leverage this sentiment to flip more Democrats like Menendez and Schumer. Had President Obama failed to gather the support needed to sustain his veto, the Republican-controlled Congress would have passed the disapproval resolution.

According to Peake, some US sanctions against Iran would have probably remained in place as a consequence. These sanctions would have hit not just Iran, but probably Washington's European allies as well, who've been moving to invest there.

"The United States would then be compelled - at least by law, the president would ignore this I'm sure - to sanction the states that are now trading with Iran and that would be our allies," Peake said.

"It wouldn't just be a loss of US credibility, it would be a serious diplomatic problem, an economic trade issue with our European partners," he continued. "That would create a schism in our relationship not just with Russia, but also with Germany and France and Great Britain."

Banks uncertain

Some European banks are observing the confrontation between the president and Congress with concern, according to Christopher Bidwell, an expert on non-proliferation at the Federation of American Scientists.

European banks have been burned by US sanctions before. Authorities fined France's BNP $10 billion (8.9 billion euros) and banned the bank from conducting some transactions in dollars for a year because it had violated US sanctions against Iran, Cuba and Sudan.

With this episode in mind, some banks might not be willing to do business with Iran even if President Obama successfully vetoes the congressional resolution. A veto would suggest that the Iran deal doesn't enjoy strong bipartisan support in the US. The presidential election is just around the corner, and the Republican candidates oppose sanctions relief.

"They may not be willing to rush into the Iranian market so fast," Bidwell told DW. "That's the impact this debate between Congress and the president has. Just because the sanctions are temporarily waived doesn't mean the risk is off."

Move to filibuster

If the sanctions are in fact lifted but the banks are simply unwilling to do business with Iran due to the political risk, Tehran might accuse the US of not holding up its end of the bargain, Bidwell said.

President Obama and his Senate allies hope to avoid the negative political fallout from a veto. They are now moving to filibuster the disapproval resolution, which would prevent it from being brought to a vote altogether. Such a move would require 41 votes.

"If they successfully filibuster it, Congress won't be on the record as diametrically opposing the president's foreign policy," Peake said. "If the Democrats can filibuster it, the president doesn't lose an embarrassing vote that might hurt our credibility internationally."