KABUL, Afghanistan — Afghanistan’s presidential elections are headed for a runoff after full preliminary results released Saturday showed the front-runners failed to win to a majority and avoid a second round of voting.

Former Foreign Minister Abdullah Abdullah garnered 44.9 percent of the vote, followed by ex-Finance Minister Ashraf Ghani Ahmadzai with 31.5 percent, said election commission chairman Ahmad Yousuf Nouristan. The candidates are vying to replace President Hamid Karzai, the only president Afghans have known since the 2001 U.S.-led invasion to topple the Taliban’s hard-line Islamic regime.

“According to our findings it seems that, this election will go to the second round,” Nouristani said. “We have a tentative schedule of June 7th to start the second round.”

The preliminary results are to be finalized on May 14 after investigations into fraud complaints. But those investigations are unlikely to invalidate enough votes change the outcome.