WASHINGTON (CNN) -- Iraq is at a "precarious juncture" after nearly four years of war, with chances for increasing stability weighed down by increased violence, corruption and sectarian division, outgoing Intelligence Director John Negroponte said Tuesday.

Negroponte's comments came as he announced that a long-awaited National Intelligence Estimate on Iraq will be sent to Congress by Monday.

"I want the NIE to speak for itself, but what I would like to say is that my belief that success in Iraq remains possible is based on my experience in dealing with Iraq as U.S. ambassador to the U.N. and ambassador to Iraq and as director of national intelligence," he told the Senate Foreign Relations Committee.

Negroponte has been tapped to replace Robert Zoellick as deputy secretary of state. He appeared before the committee for his confirmation hearing Tuesday.

The long-overdue intelligence estimate -- a classified document -- is the authoritative consensus of U.S. spy agencies. An unclassified version of a previous NIE was a key piece of evidence in the Bush administration's arguments that the 2003 invasion of Iraq was necessary to keep Baghdad from producing chemical, biological and nuclear weapons and providing them to terrorists.

A CIA-led survey later found that Iraq had dismantled its weapons programs under U.N. supervision in the 1990s, though it had tried to conceal some weapons-related research from inspectors.

"Here's what I would say: Iraq is at a precarious juncture," Negroponte said Tuesday. "That means the situation could deteriorate, but that there are prospects for increasing stability in Iraq. And achieving increased stability will depend on several factors; among them, the extent to which the Iraqi government and political leaders can establish effective national institutions that transcend sectarian or ethnic interests and, within this context, the willingness of Iraqi security forces to pursue extremist elements of all kinds."

He said other factors that could tip the balance include the ability of U.S. and Iraqi troops to stop Sunni Muslim extremists, led by al Qaeda's operatives in Iraq, from fomenting further sectarian violence between Sunnis and the country's Shiite Muslim majority -- and the extent that Iraq's neighbors, particularly Iran and Syria, stop the flow of weapons and fighters across the border.

The Bush administration has repeatedly accused Iran and Syria of meddling in Iraq, with President Bush vowing to "respond firmly" to Iranian interference in the war.

Negroponte said U.S. policy is to resolve differences with Tehran by peacefully -- "but at the same time, we don't believe that their behavior, such as supporting Shia extremists in Iraq, should go unchallenged."