Delegates from Ghana's ruling party have overwhelmingly chosen incumbent President John Atta Mills as their candidate for next year's presidential election.

President Mills won nearly 97 percent of the vote to defeat former first lady Nana Konadu Agyemang Rawlings, the wife of former president Jerry Rawlings.

Around 3,000 delegates turned out Saturday for the National Democratic Congress party primary, which was held in the city of Sunyani in southwestern Ghana.

It was the first time in Ghanaian politics that a sitting president was challenged for his party's nomination.

Rawlings announced in April she would seek the nomination, seen at the time as a sign of division among the ruling party ahead of elections set for December 2012.

Her husband, Jerry Rawlings, seized power in Ghana in successive coups, first in 1979 and then in 1981. Jerry Rawlings then served as Ghana's elected president from 1993 to 2001.

President Mills launched his campaign for re-election in May, expressing confidence he would win the nomination.

The former opposition leader took office in 2009, succeeding John Kufuor who served the maximum of two four-year terms.