Thousands gathered in the heart of New York City on Wednesday to protest the threat of the Iran nuclear deal.

Organizers estimated about 10,000 people attended the event.

At the rally, Alan Dershowitz, a Harvard Law School professor emeritus, said he was “opposing the deal as a liberal Democrat”. Al Jazeera’s Rosiland Jordan, reporting from Washington where the talks were held, said that some members of Congress came out from the discussions and told reporters that they were still very sceptical about the deal.

“That is not the way democracy should operate”, he told the crowd.

Congress disapproving the deal would remove Obama’s ability to waive most U.S. sanctions imposed on Iran, but Obama has pledged to veto a disapproval resolution if it passes.

Demonstrator Desiree Soper of Long Island said she was drawn to the protest because she wanted to voice her opposition.

The most influential pro-Israel group, the American Israel Public Affairs Committee (AIPAC), will deploy about 300 lobbyists on Capitol Hill next week to try to convince lawmakers, especially undecided Democrats, to vote against the deal, according to officials in the pro-Israel camp.

“We have to stop the suicidal agreement that permits Iran to keep a nuclear infrastructure”, Zuckerman said. But opponents of the deal say it leaves Iran’s nuclear infrastructure intact, including centrifuges and research facilities, and does not offer sufficient guarantees of transparency to ensure Tehran does not cheat on the agreement.

Under the July 14 accord, sanctions will be gradually removed in return for Iran accepting long-term curbs on a nuclear program that the West has suspected was aimed at creating a nuclear bomb.

“How can one be an Iranian and not cheer for our negotiating team?”

Conservative commentator Monica Crowley compared Iran to Nazi Germany by calling the Islamic state an “unapologetic denier of the Holocaust” and repeatedly invoking the phrase “Never again”. Rouhani added referring to Foreign Minister Mohammad Javad Zarif and the head of Iran’s Atomic Energy Organization, Ali Akbar Salehi, both of whom attended Rouhani’s speech. Well, this isn’t a bad deal, this is a God-awful deal.

“I was personally in favor of a negotiated agreement if it’s an airtight deal, if Obama kept his promise”.

The Republican-majority Congress has 60 days to review the deal.

“Clearly Iran is a much greater threat to the world than an opera”, Wiesenfeld said.

Zarif attended a parliamentary session on Tuesday to deliver the text of the deal to the MPs and answer their questions.