"Look at the young people: they don't have jobs, they can't afford to get married – it's poverty," said Hamid Reza, sitting in the café where he sells tea and hot food to neighbourhood workers. "Ahmadinejad says that when people work together they can solve all the problems in this country."
In Shush Square, voters see their Islamist mayor as an anti-establishment champion who will finally tackle widespread poverty and attack the corruption of the ruling elite. If the mayor does pull off a surprise victory in today's run-off vote against the former president Akbar Hashemi Rafsanjani, many of Iran's poor will be leading the celebrations.
Latest polls suggest the two candidates are running neck and neck as citizens vote for the second time. Mayor Ahmadinejad is clearly appealing to a wider audience than might have been expected.
Mr Reza, who is prepared to speak of his backing for the mayor, does not fit the stereotyped image liberals paint of a hardliner. He speaks warmly of the reformist Mohammed Khatami. But he harbours a simmering resentment about Mr Rafsanjani.
"Rafsanjani made so many promises as president and never fulfilled them in eight years," the café man says. "Now it's time to give the chance to somebody else," he said, to nods from customers sitting nearby.
Many other residents of this deprived neighbourhood are also angry at the perceived venality of Mr Rafsanjani – a widely held view encouraged by an illegal smear campaign, involving leaflets and CDs, for which several people were arrested on Wednesday.
The Kurdish boy serving tea from a huge samovar in the corner of Mr Reza's café is leafing through one such pamphlet, which discusses the Rafsanjani family's alleged Swiss bank accounts, foreign investments and expensive hobbies.
This ire is focused on misused oil income, an issue that helped trigger the 1979 revolution and brought people on to the streets in the Fifties to support the nationalisation of the then British-owned oil industry.
"When the oil price was $8 (£4.40) a barrel, we were poor. Then it rose to $20 and we were still poor. Now it's more than $50 and nothing's improved," said a bazaar trader and supporter of Mr Ahmadinejad, who asked to remain anonymous. "The money all goes to people who are in the government."
Mr Ahmadinejad promises to more directly distribute Iran's oil earnings of about $110m a day between the country's 67 million people. This populist tactic has alarmed Iran's modern commercial community, but the bazaar stall-keeper said more money in people's pockets would lead to brisker business for traders like him.
Mr Rafsanjani has followed suit, promising to give every adult shares in state-owned companies. He has also promised to continue President Khatami's reforms, which he says were started under his earlier stewardship.
Even some of Mr Ahmadinejad's own supporters see the blacksmith's son as potentially draconian. But others, who tend to be drawn from more socially conservative backgrounds, want to see a greater concentration on issues such as jobs and drug abuse, now rife in poorer areas.
"Rafsanjani was responsible for the moral corruption and unemployment," said a retired bus driver sitting with a friend next to the main mosque in the bazaar. "I fought at the front, now I have £50 a month as a pension and all I can see in this city are drug addicts and thieves."
Liberals see Mr Ahmadinejad, a former university professor, as the representative of repressive theocracy. But in Shush Square and Tehran bazaar, some will vote for him because they oppose rule by the clerics. Iran's last three presidents have been clerics, including Mr Rafsanjani, and despite the Tehran mayor's close relationships with the Supreme Leader and Islamic Revolutionary Guards Corps, he is seen by some people as coming from outside the old system.
Why America prefers Rafsanjani
The US would surely prefer a victory for the veteran former leader Akbar Hashemi Rafsanjani in today's presidential election run-off in Iran. Even before the vote, however, Washington has made it clear that in its view the entire process is deeply flawed – and that whatever the result, the realities of power in Tehran are unlikely to change.
For Washington and its allies, the most important issue is the halting of what they claim is Iran's pursuit of nuclear weapons. Mr Rafsanjani has promised to seek better relations with the West and find a solution to the nuclear dispute. His opponent, Mahmoud Ahmadinejad, would almost certainly be less inclined to compromise.
Even before the first round of the poll, President George Bush had all but dismissed the vote, saying that the tight vetting of candidates meant that it did not respond to the aspirations of the people.
Condoleezza Rice, the Secretary of State, dismissed the election as a sham, which "does not mask the organised cruelty of Iran's theocratic state". Some contend that the US criticism led to a partial boycott of the vote, depressing a turnout officially estimated at 62 per cent.
But other analysts say the tactic backfired, boosting Mr Ahmadinejad as conservatives flocked to the polls in protest at perceived US interference in Iran's domestic affairs.
Rupert CornwellReuse content