In many ways, Mohamed Morsi, a conservative Islamist, has been an accidental candidate in the race to become Egypt’s next president.

It was not until his mentor, Khairat el-Shater, was disqualified from the race that Morsi became the choice of the Muslim Brotherhood, Egypt’s most powerful Islamist group. Some Egyptians deride him as the “spare tire,’’ a reference to his backup role. He is an engineer and a university professor not known for gravitas or charisma.

But Morsi is very much a product of the Brotherhood, having risen through its ranks over the past two decades. The group faced criticism this spring when it reneged on a promise to stay out of the presidential race. But by Thursday night, Morsi’s apparent success in advancing to a runoff appeared to confirm the Brotherhood’s enduring reach and efficiency, unrivaled in Egypt even under Hosni Mubarak, when the group was nominally outlawed.

“It was the Muslim Brotherhood machine that brought him to this point. Morsi has modest political skills with a strong commitment to the Muslim Brotherhood ideology and leadership,” said Khalil al-Anani, an expert on Egyptian Islamist movements at Durham University in Britain. “He is a shell for the Muslim Brotherhood, and he will sacrifice himself for the sake of the Brotherhood’s survival.”

Egyptian analysts say Morsi was chosen because of his loyalty to the organization’s dominant conservative wing. During his campaign, Morsi cast himself as God’s candidate, promising that the Koran would be the foundation of a future constitution and vowing to implement a strict version of Islamic law. In recent weeks, the Brotherhood appealed to conservative clerics, asking that they urge followers to vote for him.

Morsi has said he has no plans to revise the peace treaty with Israel for now, but he has been harsh on Israelis, calling them “killers” because of their treatment of Palestinians. He has also said that women shouldn’t be allowed to run for president. He told The Washington Post in an interview last year that the ultra-
conservative Persian Gulf kingdom of Saudi Arabia was a good model for Egypt.

“Morsi is not going to betray the more conservative interpretation of the Muslim Brotherhood which now dominates,” said Joshua Stacher, an assistant professor of Middle East studies at Kent State University.

Morsi, 60, was born in the Nile River Delta. He received a doctorate in engineering from the University of Southern California and taught until recently at Egypt’s Zagazig University. His rise in the Brotherhood came with the support of Shater, the group’s top financier and strategist. Morsi led Brotherhood-aligned members of parliament from 2000 to 2005, a period in which they held 20 percent of legislative seats. Such lawmakers were shut out of the legislature after the fall 2010 elections, which were widely seen as rigged by then-President Mubarak’s ruling party.

Morsi’s biography on the Muslim Brotherhood’s English Web site describes him as a “hard worker,” an academic and a man who was arrested multiple times for his opposition to the Mubarak government, including during the early days of last year’s revolt.

In a recent interview with CNN, he struck a moderate note.

“There is no such thing called an Islamic democracy. There is democracy only, and democracy is the instrument that is present now. The people are the source of authority,” he said. “I see it being called the presidency of the Muslim Brotherhood, but it is the presidency of Egypt.”

Correspondent Ernesto Londoño and special correspondent Ingy Hassieb contributed to this report.