At the height of his cricket glory days, Imran Khan would visualise winning – standing on the podium, cup held aloft – and propelling Pakistan to victory. Last weekend, standing before a sea of supporters in Lahore, he had a similar epiphany about his political career.

"As I stood there, watching them, I knew the moment had come," Khan, who is the leader of the Pakistan Tehrik-e-Insafr party, said. "Now nothing can stop us. This is a revolution, a tsunami. We will not just win the next elections – we will sweep them."

Whether the former cricket captain can translate rhetoric into reality is hotly debated. Yet few doubt that last weekend's rally sent shockwaves across Pakistan's moribund political system.

Over 100,000 people crammed into a historic Lahore park. Many were middle-class Pakistanis – young, urban, educated – drawn by Khan's rhetoric and their anger at conventional politics.

"This is the emergence of a new force. The cry for change is resonating across Pakistan," said Ayaz Amir, a parliamentarian from rival Nawaz Sharif's party, who was there. "Young, old, professionals, women – I've never seen such people at a public meeting in Pakistan before."

The sight, Amir added, had "scared the living daylights" out of his own party.

But others are sceptical that Khan represents real change. "We've heard this rhetoric many times before," said Badar Alam, editor of Herald magazine. "I'm cautious about it. I don't know what agenda he is really promoting."

Khan is visibly buoyant. For years he has campaigned on a platform of what some call "anti-politics" – virulent criticism of the graft and patronage that infect Pakistani politics. Now, he says, he has been proved right.

Sitting on the veranda of his hilltop farmhouse outside Islamabad, he pointed across the city at the presidential palace. "[President Asif Ali] Zardari is a crook, nothing more," he said. "We've broken all records in corruption."

His plan for the economy is to "inspire" Pakistanis to pay tax – currently only 2% do so. "We just need to have some austerity and collect taxes. If we do that, we can balance our budgets," he said.

In power, Khan said, he would cut off American aid. "I want to be a friend of the Americans, not their lackey. Aid is a curse for a poor country; it stops you making the required reforms and props up crooks."

But perhaps most alarmingly for Pakistan's western allies – and some Pakistanis – Khan says he would negotiate with instead of fighting the Taliban militants who have been bombing Pakistani cities.

"Anyone who thinks this country will be taken over by Taliban are fools. There's no concept of a theocracy anywhere in the Muslim world for the past 1,400 years. If I came to power, I could end this conflict in 90 days – guaranteed."

Khan's choice of allies, many of them veterans of previous political dispensations, has also been controversial. Khan's foreign policy adviser, Shireen Mazari, is famously hostile to India; when editing a national newspaper she ran stories that branded British, Australian and American journalists as "CIA agents".

"I don't agree with her on everything. We give her hell on certain views," he says.

Yet Khan is defiantly proud that his newfound success is vindication against what he calls the "liberal, westernised elite" – wealthy, English-speaking Pakistanis who, he claims, are out of touch with the realities of their own country. "I call them coconuts: brown on the outside, white on the inside, looking at Pakistan through a westernised lens," he says.

His political views are firmly rooted in a particular view of Islam. He does not favour changes to the notorious blasphemy law – a virulent debate that led to the assassination of his friend Salmaan Taseer last January. "The time is not right. There would be bloodshed. We need to worry about other things," he says.

And he is careful to direct his barbs away from the powerful military, which controls relations with India, the US and the fight against the Taliban. Although Khan enthusiastically criticises [former president Pervez] Musharraf, who is now in exile, he has little criticism of the army chief, General Ashfaq Kayani.

"I have been critical of the generals in the past. I told them they are selling our blood for dollars," he says. "But this is not martial rule. It's up to our corrupt government to take responsibility." If he was in power and the army interfered, he says, he would resign. "We would go back to the people."

Khan enjoys a reputation for probity, having set up a cancer hospital in honour of his mother, who died of the disease. He also has a flash of glamour. A famous Pakistani pop band, Strings, opened last week's rally; supporters include his former wife, Jemima Khan, who attended a recent press conference in Islamabad to protest at CIA-led drone strikes in the tribal belt.

For some Pakistanis, Khan simply represents a protest against a moribund political system. "He's a bit of an idiot," said an architect from Lahore. "But he's better than the rest. I would vote for him."

To achieve his dream of becoming prime minister, Khan needs to convert his newfound popularity into seats in parliament (he has none, having boycotted the 2008 poll). To do so, he may have to recruit the same "corrupt" politicians to achieve a majority. "This is his most deadly flaw," says Herald editor Alam.

And time is short. Pakistan's next election is set for February 2013 at the latest, although a snap election is a possibility.

His party remains weak, he has few candidates and, crucially, many of his supporters have never voted before. Whether they will now, says Alam, is "perhaps the biggest unknown in Pakistani politics today."

Background

Although a self-styled "revolutionary", Imran Khan's politics are far from the fevered streets of the Arab Spring. The difference is democracy: whereas across the Muslim world, dissidents are fighting for the right to vote, Pakistanis already have it. But many dislike the leaders those elections have thrown up, hence the current upheaval.

President Asif Ali Zardari is an accidental leader, propelled into the job after his wife, Benazir Bhutto, was assassinated in December 2007. (Police indicted seven people for her killing last month, including two policemen, but the details remain murky.) Zardari has struggled to shake off the "Mr 10%" moniker – a reference to alleged corruption – while deteriorating economic and security conditions have plunged his poll ratings into the low teens.

But the main opposition challenger, Nawaz Sharif, has failed to capitalize on this misfortune. His N-league party, which controls the Punjab government, has grown unpopular for failing to contain an outbreak of dengue fever in recent months. Sharif is also estranged from the powerful military, which launched him into politics in the 1980s, due to his long-standing rivalry with Pervez Musharraf, the general who ousted Sharif from power in 1999.

The turmoil has emboldened challengers. One is Musharraf, who currently lives in exile in London, and has vowed to return to Pakistan next March. But the general faces numerous obstacles, including court prosecutions, security threats and opposition from the army leadership. The other is Khan, until recently viewed as a fringe player in national politics, seen most often on chatshows and protests against drone strikes.

All eyes are now fixed on senate elections next March, which should see Zardari's Pakistan Peoples Party take control of the upper house – and, possibly, pave the way for a second term as president for Zardari.