President Obama on Thursday defended the administration’s pursuit of a nuclear deal with Iran, saying that the U.S. would lose “nothing” by testing a diplomatic solution.

Obama reiterated that it was U.S. policy that “Iran cannot have nuclear weapons” and that all options were on the table to stop that from happening. But he cautioned that military action was “always messy” and brought with it “unintended consequences” and urged lawmakers to allow more time for diplomacy.

“We will have lost nothing at the end of the day,” said the president during a press conference at the White House.

“It has never been realistic that we would resolve the entire problem all at once,” Obama said in support of the short-term deal the administration hopes to negotiate with Iran.

Secretary of State John Kerry last week pushed the blueprint that would see the U.S. offer limited, temporary sanctions relief in exchange for Iran freezing elements of its nuclear program. The deal would establish the framework for continued talks after the international community confirmed that Iran was not developing nuclear weapons.

But Kerry was unable to reach a deal with Tehran and reports of the U.S. offer sparked criticism from key U.S. allies and on Capitol Hill, where lawmakers worried Obama was undermining the international sanctions regime.

Israeli Prime Minister Benjamin Netanyahu slammed the proposal as the “deal of the century” for Iran, and French Foreign Minister Laurent Fabius said it was a “sucker’s deal” that failed to impose tough terms on Tehran.

Obama on Thursday said the deal he is pushing would leave “our entire sanctions infrastructure still in place.”

“We can dial those sanctions right back up,” Obama said, if Iran failed to win the confidence of the international community.

Lawmakers are weighing passing a new round of sanctions to further heighten pressure on Iran. The administration, though, has launched a full court press to convince lawmakers to hold off for now.

“If we're serious about pursuing diplomacy, there's no need for us to add new sanctions,” the president said Thursday.

“Let’s see if this short-term, phase one deal can be completed to our satisfaction,” said Obama. “Let’s test how willing they are to resolve this diplomatically and peacefully.”