GOP presidential candidate warns of another attack on New York City if the Iran deal goes through

US Sen. Lindsey Graham (R-South Carolina) is warning that world powers' nuclear deal with Iran could lead to another attack on the United States.

Speaking at an event in New York City on Monday, Graham cautioned of the dangers of the recently announced nuclear deal with Iran. Graham, a GOP presidential candidate, ended his remarks with a stark alert for New Yorkers.

"Where do you think they'd like to come most outside of Washington? Right where we're sitting," Graham said.

"New York City represents America. This is the place that they'd choose to hit us again if they could," Graham added.

Flanked by Sen. John McCain (R-Arizona) and former Sen Joe Lieberman (D-Connecticut), Graham struck an almost-apocalyptic tone when discussing the deal. He frequently drew parallels between Iranian Supreme Leader Ali Khamenei and Adolf Hitler, claiming that the deal posed an enormous threat to Israel and to the US and that it would lead to a nuclear-arms race in the Middle East.

"A yes vote takes all the leverage off the table, locks in the deal, and makes a conflict in the Middle East much more likely," Graham said. "... The Sunni Arabs are not going to sit on the sidelines and wait for the Iranian Shiite Persians to get a nuclear weapon."

Though the Republican presidential field is universally opposed to the deal, Graham - who is currently one of the lowest candidates in the polls - is making his opposition to the Iranian deal a bigger part of his campaign. He is planning a slew of stops over the next 60 days - or until Congress votes on the deal - on a "no nukes for Iran" tour.

Speaking to reporters after the town hall on Monday, Graham said that he agreed with Wisconsin Gov. Scott Walker's (R) comments that it is "very possible" that a new president would be forced to take military action against Iran on the first day of his or her presidency.

"The military option should be on the table for any president, at any time because the consequences of a nuclear breakout for Iran are just enormous to our national security," Graham told Business Insider in response to questions about Walker's comments.

Both Graham and Walker are taking much more hard-line stances than Florida Gov. Jeb Bush (R), who said over the weekend that it would be naive not to consult with allies and key Cabinet members appointed and confirmed before proceeding to possible military options on Iran.

At the even on Monday, Graham took a dig at one of his rivals: Sen. Rand Paul (R-Kentucky).

"I'm going to say something bipartisan: Hillary Clinton could've done a better deal than this," Graham said, who later repeated the phrase and added that "almost anybody could have, except Rand Paul."

Graham rattled off numerous provisions in the deal that he found dangerous, including the eventual end of an arms embargo on Iran and the need for inspectors to give Iran 24 days' notice before inspecting at certain nuclear cites.

"Do you mind if we come by in three weeks?" Graham asked sarcastically.

Graham said that his goal for now is to rally support for Democratic members of Congress who appear to be hesitant to endorse the deal, at least for now. The South Carolina senator pleaded with traditional Israeli allies in the Democratic caucus - including Sen. Chuck Schumer (D-New York) and Sen. Bob Menendez (D-New Jersey) - to rally Democrats to oppose the deal.

Opponents need to meet at key 67-senator threshold to overcome a likely presidential veto if they vote down the deal. If they cannot get two-thirds of the House and the Senate to overturn the president's veto, the deal will automatically go through.

"The last line of defense is the United States Congress and the power of the next president to protect us and the world at large," Graham said.

Though he admitted that Republicans do not have the votes yet, Graham remained optimistic that he could convince his Senate colleagues.

"I think we could get there," Graham said.

The South Carolina senator said that his solution would be to start over on a new deal, without ending the arms embargo and with an "anytime, anywhere" mandate for inspection. Graham said he'd punish any Russian, French, and German company that sold arms to Iran.

"A better deal could be easily had only with leverage," Graham said. "If you vote no to this deal, you're giving the next president leverage to get a better deal."