US Army Chief of Staff General Martin Dempsey meets with US soldiers at Baghdad's Camp Victory April 20, 2011. [Photo/Agencies]

WASHINGTON - President Barack Obama may pick Army Chief of Staff General Martin Dempsey as the US military's top officer, filling a crucial post that in recent years has served as the main point of contact with Pakistan's military, sources said on Wednesday.

Dempsey is a leading candidate for the high-profile job of chairman of the US military's Joint Chiefs of Staff, according to the sources, who spoke on condition of anonymity.

Dempsey, who commanded troops during the Iraq war and has broad support in Congress, would replace Admiral Mike Mullen in the post. Mullen is a holdover from the Bush administration who has been in the role of top US military officer since 2007 and is due to step down on Oct.1.

As Army chief of staff, Dempsey is the top officer in the largest branch of the US military. He has served in the post only since last month.

The nomination of Dempsey would be the last major change expected in Obama's national security team following the president's April announcement of new picks to lead the Defense Department and the CIA.

If confirmed, Dempsey would work with Leon Panetta, now the head of the CIA and Obama's choice to replace the departing Robert Gates as defense secretary. Obama picked Army General David Petraeus, commander of the Afghanistan war effort, to replace Panetta at the spy agency.

Dempsey's selection would alter the chemistry of a team that will help set strategy in Afghanistan, the Middle East and for looming defense budget battles in Washington. He also would be involved in plans to withdraw US forces entirely from Iraq by the end of this year.

Mullen has worked to improve ties with Pakistan and served as the main interlocutor with Pakistan's powerful army chief General Ashfaq Kayani. Critics of US strategy toward Pakistan say that despite Mullen's efforts and some $3 billion in US aid to the country this year, Islamabad is a half-hearted ally at best in the fight against militants.

The May 2 US raid in Pakistan that killed Osama bin Laden has heightened tensions between Washington and Islamabad.

Dempsey and Kayani studied together in the 1980s at the US Army Command and General Staff College at Fort Leavenworth, Kansas, and met last month when the US general was in Pakistan, an aide said.

General James Cartwright, the current vice chairman of the Joint Chiefs of Staff, had been considered the favorite to replace Mullen but Obama informed him on Saturday he was not chosen for the job, a US official said, speaking on condition of anonymity.

The official said one concern was that neither Mullen nor Gates had endorsed Cartwright for the job, the official said.

Some top brass have complained in the past about Cartwright's leadership style. Earlier this year, he was cleared of wrongdoing by a Pentagon investigation into accusations of having an improper relationship with a subordinate.