President Obama on Saturday hailed the presidential election in Afghanistan as an “important milestone,” as the U.S. and allies ready to withdraw military forces.

“On behalf of the American people, I congratulate the millions of Afghans who enthusiastically participated in today’s historic elections, which promise to usher in the first democratic transfer of power in Afghanistan’s history and which represent another important milestone in Afghans taking full responsibility for their country as the United States and our partners draw down our forces,” said Obama in a statement.

Afghans flocked to the polls on Saturday to elect a new president to replace outgoing leader Hamid Karzai.

Reports said that election workers saw high turnout and extended polling hours to accommodate voters. The high participation was seen as a victory for the embattled government in Kabul, coming after weeks of stepped up attacks by the Taliban.

“We commend the Afghan people, security forces, and elections officials on the turnout for today’s vote — which is in keeping with the spirited and positive debate among candidates and their supporters in the run-up to the election,” said Obama.

The president said the elections were “critical to securing Afghanistan’s democratic future, as well as continued international support.”

“We look to the Afghan electoral bodies to carry out their duties in the coming weeks to adjudicate the results — knowing that the most critical voices on the outcome are those of Afghans themselves,” he added.

Reports said that it could take at least a week for officials to tally all the votes and observers predicted that it was unlikely one candidate would hit the 50 percent threshold to avoid a runoff election.

The election though comes as relations between Karzai and Obama have hit their toughest stretch, with the Afghan leader refusing to sign a post-war security agreement. Karzai has said that he would leave it to his successor to sign, despite White House pressure.

Because of the delay, Obama has ordered the Pentagon to begin planning for a possible complete withdrawal of all American forces by year's end.

The administration has warned that failing to sign the Bilateral Security Agreement, which would allow Americans to remain in the country to advise and train Afghan security forces, risks jeopardizing the decades-plus international effort to rebuild Afghanistan.

Obama also praised the American contribution to that effort on Saturday.

“Today, we also pay tribute to the many Americans — military and civilian — who have sacrificed so much to support the Afghan people as they take responsibility for their own future,” said Obama.

The administration has declined to back any candidate in the contest and Obama vowed that the U.S. would work with the leader chosen by the Afghan people.

“The United States continues to support a sovereign, stable, unified, and democratic Afghanistan, and we look forward to continuing our partnership with the new government chosen by the Afghan people on the basis of mutual respect and mutual accountability,” the president said.