TEHRAN, Iran (CNN) -- The sidewalks of Iran's capital are jammed with political rallies, just days before the Islamic republic decides on its next president.
President Mahmoud Ahmadinejad attends a rally Wednesday in Tehran.
A sea of green identifies the massive rally for reformist candidate Mir Hossein Moussavi, who is hoping to unseat hardline President Mahmoud Ahmadinejad.
Moussavi has rallied Iran's younger voters, many of whom just want Ahmadinejad out of office.
"This is like a revolution, people are excited about rescuing our country from a calamity it's been in for the last four years," says Pega, a Moussavi supporter who dons a green headband under her black headscarf.
Voters will head to the polls on Friday.
On the opposite street, Ahmadinejad's supporters, who are mostly traditional and overwhelmingly religious, wave pictures of the incumbent president as honking cars pass through the dueling sidewalk rallies. Many have been bused in to counter the ever-growing Moussavi crowds.
The Iranian president still has staunch support especially among the poor in the provinces to whom he has doled out money, benefits and favors. Watch more about the campaign »
"Honestly we have never seen anyone as courageous as Ahmadinejad," one of his supporters says.
Some say there have not been such massive rallies in Tehran since the Islamic revolution 30 years ago. Both sides plan to attend a major rally Wednesday night in Tehran's Freedom Square.
Moussavi is the main challenger trying to unseat Ahmadinejad in the heated campaign. There have been occasional scuffles at the protests in Tehran in the days leading up to Friday's vote. Moussavi's supporters organized a human chain stretching north to south through the capital earlier this week. When one of Ahmadinejad's supporters strayed into an opposition stronghold, the mood was raucous but not violent as the two camps tried to drown each other out.
A series of live televised debates has also added to the campaign drama, with the candidates hurling various accusations. Others have been drawn into the fracas, including one of Iran's most senior politicians, former President Akbar Hashemi Rafsanjani.
In his debate with Moussavi, Ahmadinejad accused Rafsanjani and another former president, Mohammad Khatami, of mismanagement, corruption and masterminding a plot against him.
Rafsanjani in turn accused Ahmadinejad of "lies and distortions." The sparring continued as Rafsanjani drafted an open letter to Supreme Leader Ayatollah Khamenei, stating that "millions of people were witness to [Ahmadinejad's] lies and distortions of the truth, which were against religion, law, ethics and fairness and were aimed at the achievements of our Islamic System."
Rafsanjani urged Khamenei to take control and "put out this fire" in the interest of national strength and unity.
Ahmadinejad's opponents blame him for the country's current weak economic situation, according toIranian-American analyst and scholar Reza Aslan.
"If this is an election that stays on domestic issues, particularly issues of the economy, then it's going to be very hard for Ahmadinejad to pull through this time," Aslan told CNN.
"There's a sort of overwhelming support now for an opening up of the country to the international community (with) some access to the free market economy because frankly, Iran's own economy is on the verge of utter collapse."
Aslan predicted that Friday's vote will result in a run-off between Ahmadinejad and Moussavi. He said he did not believe that either candidate's victory would greatly affect relations with the United States.
"The Obama administration is going to open up to Iran regardless of who wins this election," Aslan said. "But it would certainly be a lot easier, not to mention more politically palatable in the United States if it weren't Ahmadinejad."
The current Iranian president has caused an uproar with his repeated denial of the Holocaust and his comments about wiping Israel off the map.
CNN Chief International Correspondent Christiane Amanpour in Tehran contributed to this report.