President Hamid Karzai said on Thursday he is considering calling presidential elections a year early to lessen the strain that could be caused by foreign combat troops leaving Afghanistan at the same time as the nation is holding a national ballot.

The next presidential elections are scheduled for 2014 and the majority of NATO combat forces will leave Afghanistan by the end of that same year. At that time, Karzai will be at the end of his second five-year term and the constitution bars him from running for a third term.

Holding the vote in 2013 also could mean Karzai would step down earlier.

"I have been talking about this for a few months now," Karzai said. "With all the changes that are taking place -- with the complete return of international forces to their homes from Afghanistan and the holding of the presidential election at the same time -- whether that will be an agenda that we can handle at the same time."

Karzai, who spoke during a press conference with visiting NATO Secretary-General Anders Fogh Rasmussen, said no final decision has been made about early elections and that such a decision would take a long time.

He said he had been thinking and consulting for some time about either moving up the elections or speeding up the exit of foreign troops. There are positives to both the ideas, he said.

"This is a question that I've had and I've raised it in my inner circle," Karzai said. "I've not had a final decision yet, but it will not be soon."

Karzai's term expires in 2014 and the constitution says elections must be held 30 to 60 days before an incumbent leaves office.

However, Karzai delayed the 2009 presidential elections by about six months because of security concerns. A subsequent, drawn-out battle over fraud at the ballot box postponed his swearing in to November that year. So, it is unclear if he considers his second five-year term as starting from May or November 2009. Karzai has ruled out running for a third term.

An official with Afghanistan's election commission, which is in charge of conducting the poll, said preparations were still under way for the balloting in March 2014 and that no one had approached the commission about organizing an earlier vote.

"My understanding is that early elections can happen if something happens to the president or if the president resigns," said Zekria Barakzai, deputy chief electoral officer. In such a case, the commission would have three months to organize elections, he added.

Wahid Muzhda, a Kabul-based political analyst, said 2014 was an important year for Afghanistan and that holding elections while NATO troops are leaving would be difficult.

"We are not sure that the Afghan security forces are able to handle the security needed for an election," Muzhda said. "If we have it in 2013, at least we would have foreign troops to help."

Muzhda said he suspects the international community is pressuring Karzai to hold the election in 2013.

William Patey, the outgoing British ambassador to Afghanistan, told The Guardian last week that he had heard some people discussing the idea of early elections but that it had not been formally discussed by Western diplomats. "There are perfectly good arguments why 2013 would be a good time," he said. "But by holding it in 2013, you risk an argument that foreigners brought it forward so they can control it."

Rasmussen, who was in Kabul for talks on the transition of security responsibilities from the international coalition to Afghan security forces, said NATO it is on track to fully hand over responsibility by the end of 2014 as scheduled.

He also said Afghan troops would be ready to take the lead role around the country by mid-2013, allowing international combat forces to move into a support and training role.

"We will stick to the road map and we will gradually hand over by 2014," Rasmussen told Afghan special forces during his visit earlier Thursday to their main training base outside Kabul.

The security transition began last year, when NATO handed over responsibility for areas that are home to half the nation's population -- with coalition forces in those regions now in a support role. The handover took place in two stages and a third tranche is expected before a NATO summit in Chicago in late May. Another three phases are planned over the coming year.

"Thanks to the courage and commitment of the Afghan forces we will reach out common goal of a secure Afghanistan," Rasmussen said. "What I have seen makes me confident that we will fulfill our goal of handing over responsibility to the Afghan national security forces."

Meanwhile, NATO said one of its service members was killed Thursday by a roadside bomb in southern Afghanistan. It provided no other details. The death brought to 13 the number of international troops killed this month and to 104 the total so far this year.