The first round of the Iranian presidential election takes place tomorrow under the pall of crippling US-led economic sanctions and continuing US and Israeli threats to launch military strikes against the country. Six candidates will contest the poll after two of the approved eight nominees withdrew earlier this week.

The Iranian regime is determined to prevent a re-run of the “Green” movement that emerged after the 2009 presidential poll, backed by the US and its European allies. The largely upper middle class Green movement falsely claimed that the election was rigged to ensure President Mahmoud Ahmadinejad’s victory over so-called reformers Mirhossein Mousavi and Mohammed Karroubi. It staged weeks of protests aimed at overturning the result.

Last month, the Guardian Council, which vets presidential candidates, excluded Akhbar Hashemi Rafsanjani, the former president and billionaire businessman who backed and bankrolled Mousavi’s campaign in 2009. Rafsanjani represents sections of the Iranian bourgeoisie who favour a rapprochement with Washington and intensified pro-market restructuring aimed at fostering foreign investment.

The Guardian Council also excluded Esfandiar Rahim Mashaei, the protégé of President Ahmadinejad, who cannot run for a third term. Even though Iran’s Supreme Leader Ayatollah Khamenei backed Ahmadinejad in 2009, sharp divisions subsequently opened up in the so-called conservatives. The Principlist faction aligned with Khamenei has denounced Ahmadinejad over his veiled criticisms of the clerical establishment and his populist economic policies.

Following Rafsanjani’s exclusion, the “reform” faction and the Western media are pinning their hopes on cleric Hassan Rouhani. Another candidate, Mohammad Reza Aref, withdrew in his favour to avoid splitting the “reformist” vote. Both Rafsanjani and former President Mohammad Khatami, publicly endorsed Hassan on Tuesday.

Like all the candidates, Rouhani is part of the political and clerical establishment—a member of the Assembly of Experts, of the Expediency Council and the Supreme National Security Council. As Iran’s top nuclear negotiator under Khatami, he has been criticised for agreeing to the suspension of uranium enrichment during talks with the European powers in 2003-04. Those talks ultimately broke down amid strong pressure from Washington, which rejected any compromise over the issue.

The bitter experience of those negotiations hardened the Iranian regime’s stance and its determination to defend its rights under the Nuclear Non-proliferation Treaty to pursue uranium enrichment. Each candidate in the current election, including Rouhani, insists on the defence of the country’s nuclear program. Rouhani, however, argues that it is possible “to have good international interactions to gradually reduce the sanctions and finally remove them.”

The Obama administration has intensified the pressure on Iran in the lead-up to the election, announcing new sanctions last week, including against the Iranian currency and the country’s auto industry. The new measures are likely to further weaken the rial, which has lost 50 percent of its value over the past year. This will compound inflation and lead to further job losses. The US sanctions against the country’s oil exports have already sent prices for basic food items soaring and produced widespread unemployment, especially among youth.

The US also sent a message that its “military option” is ready, with leaks to the Israeli press of a successful test of a huge new bunker buster bomb that would be used against Iranian nuclear facilities. Iran has repeated denied unsubstantiated US and Israeli claims that it is seeking to build nuclear weapons.

As in 2009, Washington is undoubtedly engaged in operations aimed at influencing the outcome of the Iranian election and fashioning a regime more amenable to US interests. The US and its European allies are currently boosting their support for the so-called rebels in Syria with the aim of ousting Iran’s only regional ally, the regime of Syrian President Bashar al-Assad.

Following this week’s exposure of massive American electronic spying, one estimate put the number of pieces of intelligence gathered on Iran by one National Security Agency program at 14 billion just for March 2013, out of a total of some 97 billion items.

While intensifying sanctions that will impact on the Iranian population as a whole, the US has eased bans on certain computer equipment and programs, calculating that this will help foster a revival of the Green movement.

Even before the election is held, Under Secretary of State Wendy Sherman has already indicated a US challenge to the outcome. She branded the process as “unfair, unjust and unrepresentative” in a Senate hearing last week.

The five remaining candidates are closely aligned with the “conservatives.” Iran’s current nuclear negotiator Saeed Jalili is widely regarded as supreme leader Khamenei’s favoured candidate and has the backing of the senior hardline cleric, Ayatollah Mohammad Taghi Mesbah Yazdi. Jalili has called for “resistance” to international sanctions and no concessions on nuclear and foreign policy.

Tehran mayor Mohammad Bagher Qalibaf, a former commander of the Iranian Revolutionary Guard Corp air force and of the country’s police force, is another prominent candidate. He has been heavily critical of Ahmadinejad’s “economic mismanagement” and is known for his tough budgetary measures as mayor. Qalibaf is reportedly gaining support from middle class layers of the Green movement who back tough austerity measures that will impose new economic burdens on the working class and rural poor.

Ali Akbar Velayati, who is currently foreign policy adviser to Khamenei, has also focussed on the economy and US sanctions. He raised eyebrows in a TV debate last Friday when he criticised Jalili, and by implication Khamenei, who has ultimate control over foreign policy. Velayati said Jalili had failed to take “even one step” forward in international nuclear negotiations to alleviate the pressure of sanctions.

The focus of every candidate on the economy points to the divisions that have opened up in the ruling elite as a result of the sanctions regime. As well, there are deep fears in ruling circles over the widespread discontent and alienation in the working class and among the rural poor, who confront worsening hardships. All factions of the ruling class—conservatives, reformers and the Green movement—would quickly bury their differences in the face of any movement of the working class.

In the event that no candidate achieves an outright majority in tomorrow’s poll, as appears likely, a second round run-off between the two top vote-winners will take place on June 21.