The U.S. ambassador to the United Nations said Sunday that ally Saudi Arabia was undermining efforts to stabilize Iraq.

Zalmay Khalilzad's comments follow word from a senior defense official that a planned U.S. weapons sale to Saudi Arabia and other moderate Gulf states was expected to be a topic this week when Secretary of State Condoleezza Rice and Defense Secretary Robert Gates visit the Middle East.

Khalilzad, a former U.S. ambassador to Iraq, said an opinion column he wrote for The New York Times this month accusing U.S. allies of pursuing destabilizing policies toward Iraq referred in part to Saudi Arabia.

"Saudi Arabia and a number of other countries are not doing all they can to help us in Iraq," he said Sunday. "At times, some of them are not only not helping, but they are doing things that is undermining the effort to make progress."

U.S. officials have stepped up public criticism of Saudi Arabia but remain cautious in dealing with a crucial ally in the region.

Iraqi officials have accused Saudi Arabia of allowing a flow of funding to support Sunni insurgents and failing to prevent would-be suicide bombers from crossing the Saudi border to infiltrate Iraq.

On their trip, Rice and Gates are expected to ask Saudi King Abdullah for greater cooperation in Iraq. The United States says it will push for forgiving millions in Iraqi debt dating to the Saddam Hussein era and security help for the government of Iraq's prime minister, Nouri al-Maliki.

Two House Democrats, Reps. Anthony Weiner and Jerrold Nadler of New York, said Sunday they would introduce legislation to block the Saudi arms deal.

"We need to send a crystal clear message to the Saudi Arabian government that their tacit approval of terrorism can't go unpunished," Weiner said at a news conference in New York. "Saudi Arabia should not get an ounce of military support from the U.S. until they unequivocally denounced terrorism and take tangible steps to prevent it."

Weiner and Nadler noted that that 15 of the 19 hijackers on Sept. 11, 2001 were Saudi citizens.

A House Republican leader, Minority Whip Roy Blunt of Missouri, said he was inclined to support the sale. It is expected to total about $20 billion and would include advanced weaponry and air systems that would greatly enhance the striking ability of Saudi warplanes.

"But on these issues regarding Saudi Arabia, we have a bigger problem in the House all the time, because of the disappointments with the Saudis, who have traditionally been good friends of ours, who have been allies in the region, but continually seem to not understand the situation we're in right now," Blunt said.

"And so, the votes that we've had have been harder and harder as related to Saudi Arabia. And the administration's going to have to really make the case here that this is needed, that there are reasons beyond what we can see, that the Saudis continue to be helpful to us. And that will be a challenge for them, I think."

Khalilzad and Blunt appeared on "Late Edition" on CNN.