(CNN) -- Yemen's opposition has signed a regionally brokered deal that would result in the departure of controversial President Ali Abdullah Saleh and end the country's grinding political crisis, opposition officials told CNN.
The president has not yet signed the agreement, designed by the Gulf Cooperation Council, but is expected to do so on Sunday morning, a government official and an opposition official said.
Previous attempts to reach a similar pact -- guided by the alliance of Gulf Arab nations -- have come close to being finished, only to fall through.
While the opposition has been asserting that Saleh has been stalling and is not willing to sign the deal, Yemen's political leadership on Thursday said the hurdles toward forging an agreement were resolved.
Members of the opposition signed the deal in the Yemeni capital of Sanaa on Saturday night and the president is expected to sign the agreement there as well.
"There were small differences both sides had before signing, but we succeeded in solving the differences," said Mohammed Abulahoum, president of the Justice and Building party.
Abulahoum has helped Abdul Latif Zayani, general secretary of the coalition of Gulf Arab nations, mediate between the leadership and the opposition.
"The signing today opens the door for a better Yemen," Abdulahoum said.
Saleh, who has held power in Yemen for 33 years, is unpopular in many quarters of the country, but he has been a stalwart U.S. ally against terrorism.
U.S. Secretary of State Hillary Clinton said Yemen is in "trying times," with suppression and deaths of civilians.
"President Saleh needs to follow through on his commitment to transfer power. The government of Yemen must address the legitimate will of the people," she said in a statement Saturday.
"The United States will continue to support the Yemeni people as you work toward a unified, stable, democratic, and prosperous Yemen. We continue to call for a peaceful transition of power so that the citizens of Yemen may one day realize your aspirations," Clinton said.
Yemen has a strong presence of militants, particularly al Qaeda in the Arabian Peninsula, and the impoverished country has been wracked with violent anti-government protests calling for Saleh's ouster.
John Brennan, the top counterterrorism adviser in the White House, has urged Saleh to sign the agreement and make way for political transition.
Tareq Shami, spokesman for the ruling party, said Saleh asked Zayani to delay the signing until Sunday because it's Yemen's unity holiday.
"President Saleh will sign the GCC proposal and he asked Zayani days ago to delay the signing of the proposal until Sunday May 22, as this day is Yemen's unity holiday," Shami said.
"Zayani was pleased that he was able to help end the Yemeni crisis."