The sprawling Iqbal Park here was nearly empty at dusk on a recent evening. But the air still had the afterglow of an event last month that drew boisterous masses to its lawns to hear a former cricket hero promise to upend this nation’s political order.

It is an order that runs deep in this verdant eastern city, long the beating heart of the opposition party headed by former prime minister Nawaz Sharif, and across the nation, where Pakistan’s ruling party retains significant support. But a surprisingly enormous rally of about 100,000 people has reset the political conversation, prompting pundits and ordinary Pakistanis to deem the aging sportsman Imran Khan a real competitor.

“I never took him seriously as a politician before,” said Mohammad Shajar Abbas, 29, a used-clothing salesman who pointed the other night to the spot where he saw Khan’s speech on Oct. 30. “Now, even my family will vote for Imran Khan.”

The fresh buzz is no guarantee for Khan, who, although long admired for his philanthropy and athletic prowess, was a political also-ran for 15 years.

Despite daily political drama and occasional historic upheavals here, the foundation of Pakistani politics is made of three leaden blocks: the army, which has ruled for half the nation’s existence; the Sharif-led faction of the Pakistan Muslim League; and the Bhutto family’s ruling Pakistan People’s Party, now headed by President Asif Ali Zardari, the widower of the late leader Benazir Bhutto.

But Khan’s recent rise points to a changing Pakistan. Its cities are growing, its youth population is bulging, and its media outlets — which play to Khan’s charisma and good looks — have proliferated. Familiar politicians are widely regarded as buffoonish and corrupt. Zardari’s government is seen as ineffective and a pawn of the United States, points that Khan has emphasized. Political loyalties are shifting, analysts say, particularly among urban, middle-class young people.

“The two leading parties have bulk and the dead hand of tradition on their side,” Ayaz Amir, a prominent commentator and lawmaker from Sharif’s party, wrote after Khan’s rally. “Bereft of ideas they always were. Now they seem drained of relevance and purpose.”

No one thinks Khan’s party, Tehreek-e-Insaf, can sweep national elections scheduled for 2013, but it might win significantly more parliamentary seats than it previously held. Still, enthusiasm is rippling, and not just among young people, who do not typically vote in large numbers. Women, a rare sight at Pakistani political rallies, attended Khan’s. So did “a fair sprinkling of beards,” Amir wrote, referring to religious Muslims. One veteran police officer in Lahore — who spoke on the condition of anonymity because he is barred from political activity — called the gathering “mind-blowing” and said he had since converted 150 friends to Khan’s side.

So far, Khan’s main draw is that he is different, largely because his record is clean. Backers say that can keep him free of control by the powerful military, though he is seen as close to it.

Khan’s policies are vague. But he defends notions broadly liked in Pakistan: old-school Islam, a solid justice system and negotiations with Islamist militants, who many here see as frustrated with the state but reconcilable. He calls for politicians to declare their assets and for an end to predatory police and land-records systems that keep rural residents complacent.

“It is more the failures of the existing options . . . as opposed to the public seeing him as having matured as a politician,” said Cyril Almeida, a columnist for the Dawn newspaper who spent three weeks this month traveling Punjab province, Sharif’s stronghold. Even Khan’s supporters, Almeida said, think that “maybe he’ll turn out to be no better than the others.”

Many followers laud Khan’s defiance toward the United States. According to a U.S. diplomatic cable published by WikiLeaks and widely circulated in Pakistan, Khan told visiting American lawmakers in 2010 that U.S. policies, including CIA drone strikes, were “dangerous and in need of change.” Ijaz Chaudhry, a senior member of Khan’s party, said the candidate wants Pakistanis to be “friends, not slaves,” of the United States.

That resonates with Abbas, the clothing salesman. He grew up in Punjab, in a family that always voted for the Pakistan People’s Party. He never voted. But the shop where he works overlooks Iqbal Park, and curiosity drew him to Khan’s rally. The highlight, he gushed, was Khan’s riff about “auntie” Hillary Rodham Clinton, the U.S. secretary of state, dropping in on Pakistan at will.

“He said we are being treated like beggars. I really loved when he said that,” Abbas said with a broad grin.

But Khan fever is probably not enough. Parties win Pakistani elections, not individual candidates, and grass-roots party power rules, particularly in the impoverished hinterlands. There, patronage systems are profound, modern media hardly make a dent, and kinship-based networks drive loyalties. The influence of those networks, called biraderi, can extend into cities.

Mohammed Afzal, 24, a travel agent who was visiting Lahore from the major industrial Punjab city of Faisalabad, said he had hardly noticed Khan. He said his family’s elders had decided that it would be Sharif’s party’s “turn” to win national elections, adding that the entire clan would heed their choice.“He has no political history,” Afzal said of Khan.

Analysts say Khan’s success will depend on the candidates he fields, a process that is already provoking discomfort among party workers. Big political names — some of whom are rumored to be considering joining Khan — bring votes but almost always carry baggage. Khan has insisted that the party will not be “hijacked” and that only “clean” figures will be placed on his ticket.

A key test for Khan will be his next major rally, scheduled for late December in the southern megacity of Karachi, where entrenched parties wield ganglike control over political fiefdoms. But politically motivated violence there has led to a rise in the sentiment Khan is banking on: disgust with the current system.

“Ultimately, power corrupts a person,” said Khan enthusiast Zara Naz, 18, a microbiology student at Punjab University, a large middle-class institution in Lahore. “But he is already a rich man.”