(CNN) -- The July 2011 deadline to begin withdrawing U.S. troops from Afghanistan is unrealistic and unhelpful, Afghan Ambassador Said Tayeb Jawad told CNN's "State of the Union" Sunday.
"First, if you over-emphasize a deadline that is not realistic, you are making the enemy a lot more bold," Jawad said. "You are prolonging the war. That deadline should be realistic. The line should be based on the reality on the ground and we should give a clear message to the enemy, to the terrorists who are a threat to everyone, that the United States, NATO, Afghans are there to finish this job."
He continued, "If that's not the feeling, we lost the support of the Afghan people, and also make the neighboring countries of interest a lot more bolder to interfere in Afghanistan."
President Barack Obama and Gen. David Petraeus, who has replaced Gen. Stanley McChrystal as the top U.S. commander in Afghanistan, have said they would begin withdrawal in July 2011 depending on conditions on the ground.
Appearing on ABC's "This Week," Sen. John McCain, R-Arizona, questioned the wisdom of a firm deadline to start withdrawing forces.
"I'm all for dates for withdrawal, but that's after the strategy succeeds, not before," said McCain, the Republican presidential candidate in 2008 who was in Afghanistan for the Fourth of July weekend.
For now, McCain described the strategy as one that hasn't gone as well as hoped.
"The president should state unequivocally that we will leave when we have succeeded," he said. "If you tell the enemy that you're leaving on a date certain, unequivocally, then that enemy will wait until you leave."
McCain's GOP colleague, Sen. Lindsey Graham of South Carolina, echoed those thoughts in a separate interview from Afghanistan broadcast on the CBS program "Face the Nation."
"If you send a signal to your enemy you're going to leave at a certain date, they'll wait you out," Graham said. However, he expressed optimism that the counterinsurgency strategy now being led by Petraeus can show progress in turning over security to Afghan forces in some areas by July 2011.
"I do believe next summer we can have transition in certain parts of Afghanistan," Graham said. "Other parts will still need fighting and a firm commitment."
Overall, Graham said, he found morale on the ground "pretty good" as Petraeus assumed command of the mission.
His trip coincides with the visit to Afghanistan by Vice President Joe Biden, and Graham said Biden had assured him that any withdrawal of U.S. forces from the country would be "conditions-based" instead of launched purely for the sake of getting out without consideration for the status of the mission.
Graham joined McCain in urging Obama to clarify the conditions-based approach so that the nation's allies and enemies understand the U.S. commitment to the war.
Last week, some Democrats in Congress supported an amendment to a military spending bill that would have required Obama to give Congress a new intelligence report on Afghanistan by January and a plan for withdrawing troops by April.
If Obama fails to carry out his pledge to start bringing troops home by July 2011, Congress would need to approve additional funding for the war, the amendment said. The measure failed in a late-night vote after the White House threatened to veto the bill if it contained the amendment, but the language showed some restlessness among Democrats about the war strategy.