The White House on Friday pressed Afghan President Hamid Karzai to sign a post-war security agreement with the U.S. by year’s end, saying that the administration has “submitted our final offer on the text.”

“We are not open to rewriting it,” said White House press secretary Jay Carney of the Bilateral Security Agreement.

“This has been a prolonged and fully consultative process with the Afghan government and we look forward to an agreement that can be signed by both sides,” he added. “But we need it done by the end of the year.”

Carney said that the deadline was necessary so that the administration could make adequate preparations for any role in Afghanistan after the U.S.-led NATO coalition departs in the end of 2014.

“We can’t push it into next year and be expected to plan for a post-2014 military presence,” he said.

Carney’s comments came a day after Karzai, citing “mistrust” between Kabul and Washington, said he would not sign the agreement reached by U.S. and Afghan negotiators on the post-war role of the U.S. military in Afghanistan.

The Afghan leader said he would let his successor sign the deal. Afghan presidential elections are slated for 2014, with a new leader taking office in 2015. Those elections, though, could be delayed as Karzai searches for a suitable successor to run for the post.

The agreement must first be approved by the loya jirga, a council of elders, before being signed by the Afghan president.

The Obama administration hopes to leave a residual military force to continue training Afghan national security forces and to aid in humanitarian efforts.

Secretary of State John Kerry announced the terms of the deal earlier this week, which came after contentious, prolonged negotiations, including reports that the Afghans had demanded that Obama apologize or admit “mistakes” in the war on terror.

Karzai’s comments though could likely place the deal in jeopardy.

"It is time to get this done," said Carney on Friday.