Sens. Lindsey Graham (R-S.C.), John McCain (R-Ariz.) and Joe Lieberman (ID-Conn.) warned Wednesday that President Barack Obama’s Afghanistan war policy could be jeopardized by his insistence on a firm withdrawal date for U.S. troops.

They offered Obama high praise for his decision to relieve Gen. Stanley McChrystal as the top commander in Afghanistan and replace him with Gen. David Petraeus. But they said the decision does not solve other issues undermining the war effort, including White House disunity over the president’s Afghanistan policy and the poor relationship between diplomatic officials and the military brass leading combat operations.

“We are confident that Gen. Petraeus’ leadership will have a very positive effect on the situation in the region,” said McCain, the ranking member on the Armed Services Committee. “But we still have concerns about the civilian side and suggest that some consideration be given to reuniting” Petraeus with Ryan Crocker, who served as the U.S. ambassador to Iraq from 2007 to 2009. Crocker worked with Petraeus during his time as the commander of multinational forces in Iraq.

Graham was more critical in his appraisal of where the war effort stands. He said the Obama administration’s attachment to a date for withdrawing troops regardless of the conditions on the ground would have severe, adverse affects on the prospects for victory.

“Dave Petraeus is our best hope. If things don’t change, nobody can pull it out in Afghanistan. We’re not doing as well as I would like; there’s uneven progress. The civilian side, in my view, is completely dysfunctional,” Graham said. “If we don’t change quickly, we’re going to lose a war we can’t afford to lose.”

“The July 2011 policy is confusing,” he said of the withdrawal target date. “It undercuts the war effort, it empowers our enemies, it confuses our friends, and I think it needs to be re-evaluated.”

McChrystal tendered his resignation, which was accepted Wednesday, after making critical remarks in a Rolling Stone article of some members of the Obama administration and their handling of the war effort. The article does not officially hit newsstands until Friday, but it was published on the Internet on Tuesday.

Graham, a military lawyer who serves in the Air Force Reserves, said the comments attributed to McChrystal in the article bordered on insubordination punishable by the military code of conduct.

“The statements of the general were not only outside the norm, they really did put in question military subordination to civilian control,” Graham said.

The three Senators expressed concern that Petraeus’ takeover might not automatically solve the problems that McChrystal aired in the article.

McChrystal expressed frustration with the White House, which he believed was not fully committed to Obama’s policy — a policy that the president chose McChrystal to carry out. McChrystal also offered harsh criticism for the U.S. ambassador to Afghanistan, Karl Eikenberry, and White House special envoy Richard Holbrooke.

However, Lieberman said Obama’s comments Wednesday re-affirming his commitment to his Afghanistan policy were a positive step in turning the tide in that conflict. Lieberman strongly supported the counterinsurgency strategy used in Iraq and was one of the few Democrats to maintain his support throughout the course of the Iraq War.

“It was important to hear the president restate his commitment to that strategy of counterinsurgency in Afghanistan and to success in that strategy. And I think we have a higher possibility, I think a probability now with David Petraeus in charge, of achieving that,” Lieberman said.

“I want to stress one other thing the president said today that I thought was very important,” Lieberman continued. “He talked about how important it was that his team be unified in pursuit of the strategy he — President Obama — has chosen for Afghanistan. He said he would always welcome internal debate but would not countenance division publicly.”