Washington, February 28 (RHC)-- U.S. Secretary of State John Kerry has said that he is confident the next president of Afghanistan will sign a bilateral security deal with Washington that would authorize a long-term U.S. military presence in the country beyond 2014.

The deal could allow thousands of US troops to stay in Afghanistan for up to a decade after the end of this year. Nevertheless, despite mounting pressure from Washington, Afghan President Hamid Karzai has so far refused to sign it.

“Whether it's signed by him or not we obviously have serious reservations, but all six of the candidates for the presidency of Afghanistan have said that they will sign it,” Kerry told a group of reporters.

U.S. National Intelligence Director James Clapper also indicated before the Senate Armed Services Committee earlier this month that it would be better for Washington to wait until after Afghanistan's presidential elections in April, hoping a new Afghan president might sign the deal.

Kerry's remarks came after U.S. President Barack Obama threatened Karzai in a phone call that the U.S. would withdraw all its troops from Afghanistan if he did not agree to sign the pact.

The White House announced on Tuesday that Obama has ordered the Pentagon to begin planning for a full U.S. troop withdrawal from Afghanistan if the deal is not signed.