White House hopes for stopping a congressional challenge to the Iran nuclear deal and sparing President Barack Obama from using a veto suffered a blow when a key Senate Democrat announced his opposition.

The setback came Friday in the announcement from Sen. Ben Cardin of Maryland, top Democrat on the Foreign Relations Committee, that he opposes the deal, which he said “legitimizes Iran’s nuclear program.”

Cardin’s move doesn’t affect the ultimate outcome for the international accord to curb Iran’s nuclear ambitions in exchange for relief from economic sanctions. The White House already clinched the necessary Senate votes to ensure that even if Obama ends up having to veto a disapproval resolution set for a vote next week, his veto would be upheld.

But with that support in hand and more piling up, the White House and congressional backers of the deal had begun aiming for a more ambitious goal: enough commitments to bottle up the disapproval resolution in the Senate with a filibuster, preventing it from even coming to a final vote.

With Cardin’s announcement, that goal remains in reach, but it will be tougher to attain.

“This is a close call, but after a lengthy review, I will vote to disapprove the deal,” Cardin wrote in an opinion piece in The Washington Post. “After 10 to 15 years, it would leave Iran with the option to produce enough enriched fuel for a nuclear weapon in a short time.”

Senate Democratic leader Harry Reid of Nevada weighed in Saturday with an offer to avoid a debate truncated by a filibuster but impose the 60-vote threshold for Senate passage. That appeared aimed at assuaging Democrats uncomfortable with being accused of trying to delay such an important measure.

Cardin made his announcement as Obama met at the White House with King Salman of Saudi Arabia, in part to offer assurances that the deal signed by the U.S., Iran, Britain, France, Germany, China and Russia comes with the necessary resources to help check Iran’s regional ambitions. Saudi officials have cautiously supported the deal but are worried about enforcement and whether an Iranian government flush with cash after sanctions are lifted will wreak havoc throughout the Middle East.

Before the meeting began, Obama told reporters in the Oval Office that the leaders would discuss “implementing the deal to ensure that Iran does not have a nuclear weapon, while counteracting its destabilizing activities in the region.”

At a news conference at the Saudi Embassy, foreign minister Adel Al-Jubeir said his government endorses the Iran nuclear deal, having been assured by Obama that it will block Iran’s path to a nuclear weapon.

“We have looked at the details of this agreement and we have come to the conclusion that this does in fact meet that test,” he said. “We believe that this will contribute to the security and stability within the region.”

Al-Jubeir said Salman and Obama discussed a plan to improve American military cooperation with Saudi Arabia and other Gulf countries, announced after a Camp David summit in May that Salman declined to attend.

In contrast to Al-Jubeir’s sunny portrayal of U.S.-Saudi relations, Saudi officials in Riyadh said that the kingdom is displeased with the Iran deal and looking to expand its alliances beyond the U.S.

Saudi officials said the king sought a written agreement from Obama stating that the U.S. is “prepared to defend against any attempt that threatens the security” of the Gulf Cooperation Council, a coalition of Saudi Arabia, Kuwait, Bahrain, Qatar, the United Arab Emirates and Oman.

The officials say Obama has been hesitant to follow through because the agreement implicitly refers to Gulf concerns about Iran, and the Saudis feel Washington is unwilling to make such a commitment due to its rapprochement with Iran. The officials spoke on condition of anonymity because they were not authorized to discuss the matter publicly.

With all but a handful of Senate Democrats already stating their positions — and only two opposed to the deal — Cardin was the critical outstanding vote. In addition to serving as top Foreign Relations Democrat, he was an author of legislation providing for congressional review of the Iran deal. As a leading Jewish Democrat, he was also under strong pressure from segments of the Jewish community to turn down the deal, which is ardently opposed by Israel.

Cardin’s announcement came moments after Democratic Sen. Michael Bennet of Colorado announced that he would back the deal. Bennet, who is up for re-election next year in a battleground state, said the agreement is flawed but represents an important step toward the objectives of preventing Iran from attaining a nuclear weapon, ensuring Israel’s security and avoiding war in the Middle East.

Bennet’s support put backers of the agreement just three votes shy of the 41 they would need to filibuster the resolution and block it from passing. But Cardin’s opposition could be enough to prevent those three additional votes from emerging. Only five senators have yet to announce where they stand: Richard Blumenthal of Connecticut, Maria Cantwell of Washington, Joe Manchin of West Virginia, Ron Wyden of Oregon and Gary Peters of Michigan.

Several of those are seen as possible “no” votes. The other two senators opposing the deal are Bob Menendez of New Jersey and Chuck Schumer of New York.

In the House, some 110 Democrats were on record supporting the deal as of Friday, with around 15 opposed.

(AP)