The changes would probably take effect this summer. Defense Secretary Robert Gates has already said he will leave this year, and the White House wants to schedule Senate confirmation hearings in the coming months.
All sources spoke on condition of anonymity because the changes haven't been announced by the president.
The officials say Obama also is expected to name Lt. Gen. John Allen to replace Petraeus as Afghanistan commander, and diplomat Ryan Crocker to be the next U.S. ambassador in Afghanistan.
White House spokesman Jay Carney would not confirm the plans but did say that Obama would speak Thursday about personnel moves on his national security team. A former U.S. official said all four candidates would stand together with Obama for the announcement.
Allen, now the deputy commander of U.S. Central Command in Florida, is due in Washington on Wednesday, and sources in Afghanistan said Petraeus was also headed to Washington.
The Associated Press first reported Tuesday that seasoned diplomat Crocker was the top candidate for the Afghanistan ambassadorial post as part of a far-reaching revamping of the nation's top leadership in the conflict there, now in its 10th year. The Washington Post reported Tuesday night that a larger package of changes was likely to be announced this week.
Officials said Tuesday the White House was weighing several factors, including Crocker's role in the larger cast change in Afghanistan policy this summer and fall. Those personnel changes are unrelated to the progress of the prolonged war but come just as Obama needs to demonstrate enough success to follow through with his pledge to begin withdrawing U.S. forces in July.
U.S. military and civilian defense leaders call 2011 the make-or-break year for turning around the war and laying the path for a gradual U.S. exit by 2015. The main obstacles are the uncertain leadership and weak government of Karzai, the open question of whether the Taliban can be integrated into Afghan political life and the continued safe harbor Pakistan provides for militants attacking U.S. and NATO forces over the border in Afghanistan.
A U.S. official who confirmed Panetta's move to the Pentagon said the White House chose him because of his long experience in Washington, including working with budgets at the intelligence agency, as well as his extensive experience in the field during his time as CIA director. The official said Panetta had traveled more than 200,000 miles, to more than 40 CIA stations and bases and more than 30 countries, including Afghanistan and Pakistan.
Petraeus, who took over as Afghanistan war commander in June, has been expected to leave that post before the end of this year. His name had been floated for weeks as a possible replacement for Panetta if Obama tapped Panetta to replace Gates as Pentagon chief. Current and former administration officials noted that Petraeus would bring a customer's eye to the job as one of the key people to use and understand CIA and military intelligence during the wars in Afghanistan and Iraq.
Petraeus claims that military advances, especially in the traditional Taliban stronghold areas of southern Afghanistan, have blunted the Taliban-led insurgency and given the edge to the U.S. and its NATO partners. A planned transition to Afghan security control begins this year, and the U.S. wants to start withdrawing some of its approximately 100,000 forces in July.
Sending Crocker to Afghanistan would briefly reunite him with Petraeus, re-creating the diplomatic and military "dream team" credited with rescuing the flagging American mission in Iraq. Crocker would replace Ambassador Karl Eikenberry, a former Army general whose two-year tenure has been marred by cool relationships with major players in the Afghanistan war, including the White House, U.S. military leaders and Afghan President Hamid Karzai, administration and other sources said.
The nearly wholesale changes at the top of Obama's Afghanistan military and diplomatic lineup will leave fewer military and civilian leaders who have Obama's ear and who also have Afghanistan experience. Allen, the choice to become Afghanistan war commander, has never served there.
Adm. Mike Mullen, chairman of the Joint Chiefs of Staff, will leave his post in September after four years dominated by the ebb of the war in Iraq and the escalation of the one in Afghanistan. The top candidate to replace Mullen is Marine Gen. James Cartwright, who also has never served in Afghanistan.
Crocker, now at Texas A&M University, didn't respond to emails from the AP seeking comment. His assistant, Mary Hein, said he has been traveling for the school over the past week and was not available for interviews.
Associated Press writers Bradley Klapper, Ben Feller, Matthew Lee and Robert Burns in Washington and Deb Riechmann in Kabul contributed to this report.