By Nicole Dow, CNN

There’s a power struggle going on in the Middle East – a quiet competition between two nations over quite differing ideologies, approaches and rhetoric. The main players in this face-off? Iran and Saudi Arabia. But there’s an interesting twist.

Sectarian differences are at the root of the brewing rivalry for regional supremacy in the Middle East, a rivalry thrust into the spotlight as a result of the crisis in Syria. According to a former senior White House official, it is a case of soft power messaging vs hard power. But in this case, the soft power is coming from Tehran.

“We always think of Iran as a military dictatorship, but the Iranian message is clear, they want free and fair elections” in countries like Egypt, Afghanistan, Iraq, and also Syria, says Hillary Mann Leverett, a former White House official who worked on Middle East issues and held various roles with the U.S. State Department and the National Security Council.

In the case of Saudi Arabia, Leverett says a tougher stance has been demonstrated through the funding and training of fundamentalist Islamic groups. “They [the Saudis] support armed groups aligned with al-Qaeda – they are not mainstream Sunnis, who are not interested in killing other Muslims.”

Iran is a predominantly Shiite Muslim, non-Arab state that has found an ally in Syria through Bashar al-Assad’s regime. Sunni majority Saudi Arabia, in contrast, is an Arab state that has a close relationship with the United States, and also supports Syria’s opposition movement.

The inevitable tensions were evident earlier this month when Saeed Jalili, Iran’s top security chief, visited al-Assad in Syria. “Iran will not allow the axis of resistance,of which it considers Syria to be an essential part, to be broken in any way,” Jalili said, referring to Iran, Syria, Hezbollah and Hamas.

“The two big points of the Iranian push were for there to be a ceasefire in Syria for three months at the end of Ramadan, and that there should be free and fair elections,” Leverett said. “The Iranian message and belief is – if a country has free and fair elections, it will pursue independent policies that are in that country’s national interest. The Iranian belief is that if they pursue independent policies, they will inevitably be unenthusiastic about pursuing U.S. or Western policies.”

Leverett believes that Iran can apply its policy of supporting free and fair elections to Syria, despite the Syrian population being mostly Sunni, not Shiite. And this is not because Iran necessarily believes that any elected successor to al-Assad will be pro-Iranian or Shiite. “Rather, a free and fairly elected successor to al-Assad would not be interested in strategic cooperation with the U.S. and would not be interested in aligning itself with Israel,” Leverett says. “That would be completely against the views and histories of the people….For Iran that is an absolute net gain in geopolitics.”

Saudi Arabia, she says, is unable to take a similar tack.

“The Saudis cannot call for a ceasefire or for free and fair elections because the Saudis haven’t had free and fair elections in their own country. It doesn’t sound genuine, so they can’t do it, and they don’t want to do it,” she says. “No precedent has been to set to have everyone else doing it except them.”

But Leverett adds that there’s self-interest at stake, too. “The basic thing is, the Saudis aren’t interested in an outcome in Syria that leads to a government that carries out the interests of the people of Syria,” she says. “What the Saudis are interested in is a head of state who will be on their side. And their side is against Iran and its influence in the region. This is a big albatross that Saudi Arabia has on its neck.”

Geopolitics aside, though, sectarian differences are also constantly bubbling under the surface. “They [Saudi Arabia] also want to portray [it as] the Iranians don’t stand for Muslim causes, beliefs, independence or nationalism,” Leverett says. “The Saudis want others in the region to see the Iranians as Shiite, Persian, non-Arab, non-Sunni, and that what the Iranians are doing has nothing to do with democracy or freedom, but rather promoting a narrow sectarian vision. While the Saudi message is that the Shiites are infiltrating Arab affairs to undermine the Sunni community and the Sunni state.”

“They see the Shiites as heretical, non-believing, non-Arab Persians. Some Sunnis believe that, and the Saudis back that up with a tremendous amount of money and weapons,” she says.

The numbers would certainly seem to bear this out. Last year, Saudi Arabia reportedly purchased as much as six times as much military equipment from the United States last year as Iran's entire official defense budget. And the quality of its weapons systems also outshines that of Iran.

“Iran is not buying bullets, guns, and tanks,” Leverett says. “No one will sell it to them. They also want to be independent. The money they put in their military is for indigenous production.”

Included in recent U.S. weapons contracts to Saudi Arabia were reportedly F-15 fighter jets and Apache and Black Hawk helicopters.

All this means that casual perceptions of the tensions in the Middle east are worth closer scrutiny if the U.S. and others want to understand the regional dynamics – and how they may play into security issues aside from Iran’s nuclear program.

“The Islamic Republic [of Iran], we think of it as aggressive, has not threatened to invade other countries [since becoming an Islamic Republic in 1979],” Leverett says. “That’s where the conflict is today. It’s a battle today between this message that Iran has to promote of freedom, and the Saudis that are really trying to fight that message.”