The unexpected appearance of Hosni Mubarak’s last prime minister in the runoff of Egypt’s first post-revolutionary presidential race owes much to support from business tycoons and other backers of the old regime.

The candidate, Ahmed Shafiq, 70, gained enormous popularity during the final stretch of the race by appealing to weary Egyptians’ desire for a return to the stability of the old Egypt. But even some supporters acknowledge that he also drew on money and expertise from a vast network of Mubarak’s former supporters, whose National Democratic Party is now banned.

A former air force general, Shafiq finished second in the first round of balloting and faces the Muslim Brotherhood’s Mohamed Morsi in a presidential runoff next weekend. A victory by Shafiq would be seen as a defeat by many who took part in the wintertime revolution last year that ousted Mubarak.

A ‘strange’ turn of events

Some of Shafiq’s rivals have raised questions about the network that aligned behind him. In an interview, Amr Moussa, a former foreign minister, alluded to the mass mobilization of former Mubarak supporters by saying that “something strange” happened in the last weeks before the election.

Moussa stopped short of accusing Shafiq’s campaign of misconduct but said he believed that Shafiq had engaged in “manipulation’’ of a patronage system.

“Everyone is talking about the revival of the machine,’’ Moussa said, expressing concern that Mubarak-era figures will return to positions of influence if Shafiq is elected — a concern that had also been expressed about Moussa himself.

Figures from the Mubarak era can be found throughout Shafiq’s campaign team.

Former aides and deputies who worked for him when he was the country’s minister of civil aviation, from 2002 to 2011, are running Shafiq’s campaign. His campaign manager is Ibrahim Manna, who succeeded Shafiq as minister of civil aviation under Mubarak. His campaign coordinator, Mohammed Qadri, was his deputy at the ministry and has remained with him since.

Other support has come from wealthy businessmen whose companies had close ties to the Mubarak government. A production company owned by Mahmoud Baraka, which also produces shows for state television, donated its services to the campaign. An advertising firm run by Tarek Nour, which designed materials for Mubarak’s presidential campaign in 2005, designed Shafiq’s billboards.

Shafiq did not declare his candidacy until April, much later than his rivals. The idea that he could become president was at first dismissed by the secular forces who took the lead in Egypt’s revolution as well as by Islamists, who assumed that anyone so closely tied to the regime could not fare well in the balloting.

Candidacy was disputed

At one point, Shafiq was disqualified from the race under a law passed by the country’s new parliament that prohibited candidates who had served under the previous regime. His candidacy was reinstated by a presidential election commission, although the country’s constitutional court has yet to rule on the dispute.

In the first round of balloting last month, Shafiq won nearly a quarter of the votes cast. He paid just $500,000 for the billboards, which had been erected before the election to promote public awareness and were awarded to him because of his presidential qualities and non-Islamic background, said Ahmed el-Shannawy, who works for Nour’s advertising agency.

It was outside Cairo where the activation of the National Democratic Party network was key.

In the farming and working-class province of Qalyoubia, just outside Cairo, Shafiq’s support came from wealthy businessmen such as Yassir Hagag el-Falah, a 46-year-old from one of the area’s most influential families.

“I’m sick of these people who are considered progressive and revolutionary when they are the furthest thing from these words,” Falah said in a recent interview near the Shafiq campaign headquarters in his neighborhood of Shubra el-Kheima, where his father had been an NDP leader.

“This proves that a very big sector of the Egyptians were supporting Mubarak,’’ Hussein Abdel Fatah, 43, a member of another influential family, said of Shafiq’s strong showing in the first round of the elections. He said that he and other members of the NDP had initially been silent to avoid clashes with those who supported the revolution. “Now they are back on the scene,’’ he said.

Using an ‘iron fist’

Shafiq’s success has enraged revolutionaries, Islamists and some moderates, who are worried that he will return the old order and continue Egypt’s history as a police state run by a military autocrat.

But dramatic pieces on state television and in newspapers about the rise of Islamists and the lack of security played into Shafiq’s campaign, said Shahira Amin, a former anchor at state-run Nile TV who resigned in protest over the network’s pro-Mubarak stance during last year’s revolt.

In Cairo, the Shafiq headquarters is run out of the real estate office of mogul Hafez Orabi. Bodyguards sit inside, muscles bulging from their tight T-shirts, to protect the building. In campaign speeches, Shafiq has appealed to Egyptians’ desire for greater security, promising to “neutralize” the rise of Islamists and to use an “iron fist” to secure Egypt and hold rowdy protesters accountable. In a recent news conference, he warned voters that a victory by Morsi of the Muslim Brotherhood would leave Egypt beholden to the organization’s conservative Islamic ideology.

“Shafiq voters are poor people in the villages and upper Egypt and many, many women,” said Qadri, the longtime Shafiq aide. “They know the consequences of a Brotherhood president because they know the Brotherhood.”

But when Qadri stepped outside to meet with Shafiq supporters from Egypt’s Minya province, the group was dominated by retired generals.

“Shafiq has principles, he’s proud that he was a student of Mubarak, and until now he continues to say that,” said Mohammed el-Owasy, the governor of a small village outside the city of Minya.

Special correspondents Ingy Hassieb and Haitham Mohamed contributed to this report.