Army Gen. David Petraeus will walk into a “dysfunctional” military-civilian relationship if confirmed as the next top U.S. military commander in Afghanistan, Sen. Lindsey Graham (R-S.C.) said Sunday, while Sen. Jack Reed (D-R.I.) defended U.S. Ambassador Karl Eikenberry and other administration officials.

President Barack Obama nominated Petraeus, the chief of U.S. Central Command, to replace Army Gen. Stanley McChrystal last week, and hearings on Petraeus’ nomination are scheduled to begin Tuesday in the Senate Armed Services Committee. The president accepted McChrystal’s resignation last week over critical comments the general and his aides made to Rolling Stone magazine about the administration’s leadership of the war.

Reed batted down a suggestion by Sen. Saxby Chambliss (R-Ga.), who said that McChrystal’s departure is an opportunity for the “president to look at both the civilian side and the military side” in Afghanistan. They appeared on CNN’s “State of the Union,” while Graham appeared on “Fox News Sunday.”

“They all retain the confidence of the president,” said Reed, who sits on the Senate Armed Services Committee with Graham and Chambliss.

But another Senate Democrat, Intelligence Chairman Dianne Feinstein (Calif.), argued it was time to “put all of our eggs in the Petraeus basket” — and if the general cannot work with Eikenberry or Richard Holbrooke, the special U.S. representative to Afghanistan, they should be replaced, she said.

Feinstein also said the administration’s July 2011 deadline for Afghanistan should be met at Petraeus’ discretion. “I think he has flexibility” in guiding a U.S. withdrawal, she said.

Graham expressed concern that the administration has been unclear whether July 2011 represents a hard departure date or a goal for beginning a transfer of power.

Reed said the military is on track to begin withdrawing troops from the war-torn Central Asian country next summer, while adding, “It won’t be a complete pullout.”

“The withdrawal will be subject to the commanders on the ground,” he said.

Matthew Murray contributed to this report.