KABUL, Afghanistan — The Afghan president urged tribal elders Thursday to support a security deal with the United States, but in a surprising about-face said he would defer the signing of the agreement to the winner of next year's presidential elections, which he is barred from contesting.

Hamid Karzai's statement came after days of negotiations between Afghan and U.S. negotiators eager to finalize the text before the Loya Jirga, a consultative council of elders and other dignitaries who hold the power to derail the pact.

In a last-minute bid to bolster support, President Barack Obama sent a letter promising that the U.S. will continue to respect "Afghan sovereignty" and promised that the U.S. military will not conduct raids on Afghan homes except under "extraordinary circumstances," involving urgent risks to U.S. nationals. The statement referred to night raids, which have been a particularly sensitive issue to the Afghans.

Obama also said "we look forward to concluding this agreement promptly" in the letter, which was read by Karzai to the 2,500 member council.

Karzai's suggestion to push the signing of the Bilateral Security Agreement until after the April 5 elections could be a deal breaker since the U.S. wants an agreement as soon as possible to allow for preparations to maintain a military presence after 2014, when the majority of foreign combat forces will have left Afghanistan. The U.S. had wanted a deal signed by the end of October.

"If you accept it and Parliament passes it, the agreement should be signed when the election is conducted, properly and with dignity," Karzai said toward the end of a speech that lasted more than one hour.

It was unclear if the mercurial Karzai would indeed wait for the elections or sign the agreement if approved by the Loya Jirga and the parliament. He could also be waiting for the Jirga to ask him to sign it.

Karzai has in the past made inflammatory remarks only to then change his mind. He signed a strategic partnership with Obama last year despite criticizing the United States for its military actions in Afghanistan, including night raids against Afghan homes and airstrikes that resulted in civilian casualties.

His reticence to sign could also be attributed to his awareness that previous leaders of his country historically have been punished if seen as selling out to foreign interests.

Government officials and the president's office were not immediately available to comment on the unforeseen development, which came just a day after U.S. Secretary of State John Kerry said he and Karzai had agreed on the language of the pact.

U.S. Embassy spokesman Robert Hilton said he could not comment because it is an ongoing diplomatic discussion.

The Loya Jirga can revise or reject any clause of the draft agreement, but its decisions are not binding. Then the deal still must be approved by the Afghan parliament, which could ask for more changes.

The Loya Jirga will hold a series of closed-door meetings until Sunday, when it makes its suggestions on the security deal to Karzai.

On the U.S. side, only Obama's administration needs to approve the agreement, but it could reject changes made by Afghan officials. If it does, that leaves open the option for the U.S. to pull all troops out of Afghanistan. The same could happen if the deal is not signed in a timely manner.

Such was the case in Iraq, when the U.S. and Iraq couldn't agree on terms of a security arrangement. Sectarian violence has plagued Iraq since, and some fear Afghanistan could follow that path without a continued U.S. presence if Afghan forces cannot defend the country themselves.

Karzai cannot run for a third five-year term and 11 people have been approved by the electoral commission to run in the elections. Although most have declared their willingness to sign a deal, a number of high-profile candidates could be opposed. They include Abdul Rab Rasoul Sayyaf, an influential lawmaker with a long history as a jihadi and allegations of past links to Arab militants including Osama bin Laden.

Karzai told the delegates to the Loya Jirga that his decision had to do with the lack of trust between him and the United States.

"It all turns to trust, and between me and American there is not very good trust," he said. "I don't trust them and they don't trust me, the last 10 years has shown this to me. I have had fights with them and they have had propaganda against me."

Karzai said that waiting for the elections would prove America's commitment to Afghanistan's security and safety.

According to a draft agreement posted on the website of Karzai's office, the agreement gives the U.S. legal jurisdiction over troops and Defense Department civilians, while contractors would be subject to the Afghan judicial process. Deep divisions in Afghanistan over legal immunity for American soldiers and contractors as well as night raids had threatened to scuttle diplomatic efforts.

Karzai said the deal would pave the way for 10,000 to 15,000 U.S. troops to stay in the country after the NATO combat mission ends at the end of 2014 and give the United States nine bases around the country that it can use.

U.S. officials have not yet disclosed the number of U.S. troops they want to keep in Afghanistan after 2014. U.S. officials have said the U.S. and NATO could keep between 8,000 and 12,000 troops there. Of those, the U.S. is expected to provide no more than 8,000.

Associated Press writer Rahim Faiez contributed from Kabul.