Admiral William Fallon, who is poised to become the top American commander in the Middle East, says the US miscalculated the ability of Iraqi forces to take control and underestimated the enemy’s persistence. “Securing the stability of the country has been more difficult than anticipated,” Fallon said in a written statement to the Senate Armed Services Committee. “Our ability to correctly assess the political, economic and security situation in Iraq has been lacking.”Fallon’s remarks were submitted in advance of a confirmation hearing on Tuesday. Fallon, who commands troops in the Pacific region, has been tapped to replace Army General John Abizaid as head of the US Central Command.The Senate Foreign Relations Committee was expected to consider the nomination of John Negroponte, the first director of national intelligence, to become deputy secretary of state.Fallon and Negroponte’s confirmations were not expected to rouse Senate protests, despite bitter opposition in Congress to Bush’s plan to send 21,500 additional troops to Iraq.Public sentiment has turned strongly against a war that has dragged on for nearly four years with more than 3,000 American dead and violence unabated by insurgents and sectarian militias.In remarks prepared for a speech, Senator Bill Nelson, a member of the Armed Services Committee who recently returned from a trip to the region, said only another 200,000 or 300,000 US troops would make a substantial difference in Iraq.“Based on everything I saw last month, and based on my conversations with Iraqi officials, our own military leaders and rank-and-file soldiers, I am convinced more troops won’t end the sectarian violence,” Nelson said.Nelson also was expected to deliver a sharp rebuke of Iraqi Prime Minister Nouri al-Maliki.