The appointment of Vice President Goodluck Jonathan as Nigeria's acting leader opens the field for the ruling party's candidate for 2011. Lawmakers made the move more than 10 weeks after President Umaru Yar'Adua left for a hospital in Saudi Arabia.
President Yar'Adua's prolonged medical absence has made it increasingly unlikely that he will run for re-election next year.
But prospective candidates in the ruling party were reluctant to move too publicly in case he returned to power in Abuja.
The appointment of Mr. Jonathan as acting leader changes that dynamic because the vice president is ineligible to run in President Yar'Adua's place given the unofficial understanding between the country's political parties that Nigeria's presidency it to be rotated between north and south.
If President Yar'Adua is unfit to stand for re-election, the ruling party will nominate another northerner to fill the second four years of the region's allotted eight-year term. If this acting presidency continues, political observers say the front-runner for that nomination will be the man the party chooses as Acting President Jonathan's Acting Vice President.
Mr. Jonathan is from the south. Concern that transferring power to him would disrupt the country's informal power sharing was one of the biggest reasons northern politicians opposed the move.
Senate President David Mark met with northern politicians to reassure them that nothing has changed. "This basically is to allay the fear of those who feel that the acting president means that His Excellency The President Alhaji Umaru Musa Yar'Adua has been removed from office," he said.
"That is not the thing. We don't want people to spread that rumor. He remains the president. But since he is not here, there is somebody who is officially designated to act for him. I know that this type of rumor gains ground easily. That is why we took pain to emphasize this and explain it to the nation," he added.
Acting President Jonathan says he is pressing ahead with preparations for next year's elections. He says those suspected of trying to disrupt last week's gubernatorial vote in Anambra state will be prosecuted as a warning ahead of future balloting.
Mr. Jonathan met with U.S. Assistant Secretary of State for African Affairs Johnnie Carson about the 2011 election. Mr. Carson pledged Obama administration support.
"We do this as a friend. We do this as a partner," he said. "We do this because Nigeria is a democracy. And we would like to see Nigeria continue on along an upward democratic course."
If this temporary presidency carries over into next year, Mr. Jonathan is not expected to run for re-election as the southern vice president on a ticket headed by a northerner. That opens prospects for who would be the southern vice presidential nominee, who might then be considered the ruling-party front-runner when the presidential nomination shifts back to the south in 2015.
For his part, Acting President Jonathan is moving to put the ruling party on course for next year's vote by focusing on key economic issues. "We see a need to prioritize on a few of the most critical areas that have continued to plague our efforts at engendering meaningful economic growth and development. Some of these critical sectors include power, infrastructure, security, generation of employment, and business opportunities for our teeming young men and women," he said.
His acting presidency is not without challengers. Supporters from President Yar'Adua's home state plan to contest his appointment in court because it was made on the basis of a radio interview about the president being out of the country not on the basis of written notification as specified in the constitution.