ABU DHABI, UNITED ARAB EMIRATES — Secretary of Defense Robert M. Gates acknowledged Thursday that the Bush administration underestimated the difficulty of getting a political truce in Iraq, where Prime Minister Nouri Maliki's government has been crippled by a walkout by Sunni Arab ministers.
Gates said he was optimistic about military progress in several Iraqi regions, particularly Al Anbar, a western province that was once a haven for insurgents.
But he said he was discouraged by the Shiite-dominated government's inability to reach a compromise to pass legislation aimed at reconciling the country's ethnic and sectarian groups. Reaching such political agreements, a central goal of the troop buildup strategy, may still be a long way off, he said.
"I just think in some ways we probably all underestimated the depth of the mistrust and how difficult it would be for these guys to come together," Gates said.
The Pentagon chief's remarks Thursday were his closest yet to acknowledging that the Bush administration's top political goals for Iraq may not materialize during the buildup, even if it is extended into next spring, the latest the military could sustain the increase. He also is the top Bush administration official to express such concerns publicly.
The Defense secretary was speaking to reporters aboard his plane as he headed back to Washington after a three-day, four-country visit to urge Sunni Arab allies in the region to do more to support the Maliki government.
Until now, Gates has been circumspect in his assessment of the "surge" strategy launched in February, and has been careful not to wade into the political fight between the White House and Capitol Hill over its duration.
Although Gates did say in testimony on Capitol Hill that he would like to see the "surge" end by December, a senior Defense official familiar with his thinking said those views had "been overtaken by events." Gates, the official said, is waiting for an evaluation due next month from Army Gen. David H. Petraeus, the top commander in Iraq, to decide how long to continue the security plan.
The Bush administration's benchmarks for progress include passing laws to divide the nation's oil wealth, set dates for provincial elections and allow former members of Saddam Hussein's Baath Party, predominantly Sunni Arabs, to obtain government jobs and pensions.
Gates highlighted progress being made in local and provincial governments, another sign that Pentagon strategy may be shifting away from trying to impose a top-down solution to Iraq's sectarian conflict.
"The developments at the local level I think are more encouraging than I would have expected three or four months ago," he said.
Shifting focus away from the central government and toward provincial leaders would be a significant change for the administration, which has said the troop increase was aimed at calming violence enough to allow for political reconciliation at a national level.
Gates was careful not to say he had given up on national leaders.
"I think the developments on the political side are somewhat discouraging at the national level, and clearly the withdrawal of the Sunnis from the government is discouraging," he said. "My hope is it can all be patched back together."
But he said such progress would be dependent on Iraqi army and police forces holding difficult neighborhoods, an effort that has proved elusive.
In Baghdad, Maliki's party urged the main Sunni Arab bloc to reconsider its decision to quit the Cabinet. Maliki had not accepted the resignations Thursday, said Sami Askari, an aide to the prime minister and a member of his Islamic Dawa Party, a Shiite group.
In a statement, the Islamic Dawa Party said it was concerned that the Sunni bloc had quit "before exhausting all means of dialogue."
"The current situation in Iraq and the continued terrorist operations targeting innocent civilians and infrastructure demands national solidarity," the party said.
U.S. officials had hoped that including members of the Sunni Arab minority in the Cabinet would give them a stake in Iraq's political process and undercut support for the insurgency. But a year later, Sunni Muslim politicians complain that they have nothing to show for their participation.
"The issue cannot be resolved with appeals alone," said Iyad Samarrai, secretary-general of the Iraqi Islamic Party, a leading member of the Sunni coalition, known as the Iraqi Accordance Front, or Tawafiq. "The basis of the problem must be resolved."
The Sunni bloc, which had been boycotting Cabinet meetings since late June, had given the government a week to respond to a list of demands, including the release of detainees not charged with specific crimes, the disbanding of militias and inclusion of all major groups in security decisions. Maliki's office had called the move political blackmail.