WASHINGTON – Gen. David Petraeus left open the possibility of recommending that President Obama delay his plans to start withdrawing troops from Afghanistan next summer if the new commander can’t turn around the stalemated war.

“There will be an assessment at the end of this year after which undoubtedly we’ll make certain tweaks, refinements, perhaps some significant changes,” Petraeus told a Senate panel Tuesday of the battle plan and the timeline Obama has laid out.

The Senate Armed Services Committee quickly approved Petraeus for the job of running the Afghan war, and the full Senate could act as early as Tuesday evening. Obama nominated Petraeus to take over from the disgraced Gen. Stanley McChrystal, fired last week for disparaging remarks about his civilian bosses.

Petraeus also told senators that he may change the war’s battlefield rules, designed to limit civilian casualties and improve support for the foreign forces fighting the Taliban-led insurgency. Some troops and congressional Republicans say they handicap U.S. forces.

Obama has said troops will begin to leave in July 2011, but that the pace and size of the withdrawal is conditional.

Petraeus did not rule out a significant exodus then, as Vice President Joe Biden favors, but he would not promise one either. Petraeus has previously said that he would recommend putting off any large-scale withdrawal if security conditions in Afghanistan can’t sustain it.

The general, credited with turning around the Iraq war after the height of sectarian violence there in 2006, told the Senate panel that Obama wants him to provide unvarnished military advice.

He did not paint a rosy picture on Tuesday.

“My sense is that the tough fighting will continue; indeed, it may get more intense in the next few months,” Petraeus said.