The Obama administration is showing no signs of backing away from its plans to seek U.N. approval of the Iran deal early next week — before Congress has a chance to review its details — and is even ratcheting up its rhetoric about the international pressure Congress will face if it disapproves the agreement.

"For the United States, because of congressional action, to isolate our country on such an important issue would be devastating to our standing in the world," White House press secretary Josh Earnest said Friday.

"The international leverage that the U.S. and other world powers have would vanish and Iran would still be able to attain the financial benefits of sanctions relief" when other countries repeal their sanctions, he said.

"Congress can vote to let Iran off scot-free," he added, although he clearly encouraged Congress not to do that and instead said members should support the deal.

Members of Congress on both sides of the aisle over the last 48 hours have been outraged over the administration's plans to seek U.N. approval of the deal, which would lift many sanctions on Iran, before Congress has a chance to weigh in, and are pressing U.S. officials to reconsider.

But Earnest said Wednesday that the administration is pressing ahead with its plans to take it to the United Nations. And, he argued, the U.N. "acting promptly" to take it up only makes sense because the agreement is not just between the U.S. and Iran but those countries who also negotiated the deal, including all the permanent members of the U.N. Security Council.

The United Nations Security Council's approval of the deal will not impact U.S. sanctions, he stressed. "They don't have jurisdiction on that and they don't have an impact on that," he said.

He also stressed that the U.N. approval won't go into effect until after 90 days, allowing Congress plenty of time for its own 60-day review and an up or down vote on the deal.

Asked whether the administration would go back to the U.N. to re-impose the sanctions if Congress disapproves the deal, Earnest declined to speculate.

"I would not speculate if Congress were to succeed in the devastating effort to undermine the successful implementation of this agreement," he said.

But several senators, still smarting from being sidelined from the direct negotiations with Iran over the past two years, argue the move is undemocratic and violates the constitutional requirement that the Senate provide advice and consent on all international treaties. The deal as negotiated, however, has not been presented to Congress as a treaty.

They are also accusing the White House of trying to outmaneuver Congress to apply additional international pressure for them to go along with the deal.

Sen. Bob Corker, a Tennessee Republican who chairs the Foreign Relations Committee, called the move an "affront to the American people" and Congress. He and Maryland Sen. Ben Cardin, the panel's ranking Democrat, sent a letter to the white House Thursday asking the administration not to move forward with its U.N. plan.