White House officials said Tuesday that their plan for enacting the Iran nuclear agreement is to first get the United Nations to agree to its terms, including a gradual easing of sanctions, which will put more pressure on Congress to go along with what the world has already approved.

In a call with reporters, officials said the sanctions against Iran that eventually prodded them into negotiations were international sanctions, and said it's now up to the U.N. to vote on the deal announced Tuesday morning.

"We put sanctions in place to get a diplomatic resolution, and that is what we have done," he added.

While many Republicans indicated they oppose the deal, the Obama administration isn't giving them much time to organize. It plans to seek a U.N. Security Council resolution enshrining the steps Obama laid out for phasing in sanctions relief as early as next week.

It will be much tougher for detractors on and off Capitol Hill — such as Israel — to stop the arrangement once the U.N. signs off on it.

Congress is still free to try to dismantle the agreement by voting it down. But a resolution disapproving of the agreement can be vetoed by Obama, which would require a two-thirds majority in both chambers to override Obama's veto, and Obama said early Tuesday he would veto any effort to derail the deal.

Even if it's possible to kill the deal in Congress, key administration officials and Obama warned that doing so would backfire, since the rest of the world wants a deal and would balk at extending new sanctions against Iran.

"Without this deal, there is no scenario where the world joins us in sanctioning Iran until it completely dismantles its nuclear program," Obama warned. "Nothing we know about the Iranian government suggests that it would simply capitulate under that kind of pressure. And the world would not support an effort to permanently sanction Iran into submission."

Beyond veto threats and promises of United Nations action, the White House also offered praise to coax lawmakers into supporting the agreement.

"Today, I want to thank the members of Congress from both parties who helped us put in place the sanctions that have proven so effective," Obama said.

Obama called congressional leaders Monday night to keep them in the loop and plans to continue talking to key lawmakers as debate on Capitol Hill begins. He will also personally speak to Israeli Prime Minister Benjamin Netanyahu and King Salman of Saudi Arabia to try and assuage their concerns, and would speak with other world leaders throughout the day, the White House said.

Officials said Obama would likely continue to speak out in favor of the agreement in the coming weeks. They said Obama would "look for opportunities to make the case directly to the American people," and said that despite the "heated" debate in Washington, there is "broad support" among the American people to finalize the deal.