Voting begins in war

Damascus, Syria (CNN) -- Polls for the Syrian presidential election opened Tuesday against the backdrop of a bloody and protracted civil war.

The outcome is hardly in doubt: President Bashar al-Assad is almost guaranteed to emerge victorious in a vote that opposition groups and many Western countries say has been be rigged from the start.

Syria isn't renowned for holding free and fair elections.

When al-Assad came to power 14 years ago, he ran unopposed, securing more than 99% of votes, according to state media. Seven years later, he won again with a similarly mountainous share of the vote. His father, Hafez al-Assad, ruled Syria with an iron fist for 29 years before he died in 2000.

The Syrian regime says the election has to be held under the new constitution and shows the country is moving forward.

Assad marches to re-election Kerry defends diplomacy in Syria Russia, China veto Syrian war crime probe

But some analysts say the purpose of this week's vote, which U.N. Secretary General Ban Ki-moon urged the Syrian government not to hold, is to send a message to al-Assad's opponents, both in Syria and abroad.

Syria's presidential election: How fair can a vote be in a war zone?'A coronation'

'It's a coronation of Assad, it's a celebration of his ability to survive the violent storm and basically go on the offensive,' said Fawaz Gerges, a professor of international relations at the London School of Economics.

The election takes place amid a grinding three-year conflict that has killed around 150,000 people, displaced about 6.5 million people within Syria and prompted almost 3 million people to flee outside its borders.

Voting will only take place in areas controlled by the regime. Rebels hold significant parts of the north and east of the country.

There are concerns that the election process could be disrupted by violence, with voters wary of the threat of car bombs and shelling at polling stations within range of rebel mortars.

The British Foreign Office has said the vote 'will be a grotesque parody of democracy.' The U.S. State Department says the Assad regime has taken steps 'to make it difficult if not impossible to have a fair and free election in Syria.'

The regime has said election monitors from the United States, the European Union or the Organization for Security and Cooperation in Europe won't be present, but observers from some other countries will be in attendance.

Little known challengers

One aspect of this year's election distinguishes it from the previous foregone conclusions, though. Al-Assad actually has people running against him -- although it's questionable how much of a challenge they present.

The two other candidates are relative unknowns: Hassan al-Nouri, a businessman and former government minister; and Maher Hajjar, a lawmaker.

Critics say they are just pawns or window dressing to give the election a veneer of democracy. But the Syrian government has dismissed any criticism of the process.

Hajjar has kept a low profile, but al-Nouri says he's serious about challenging al-Assad and is 'trying to attack his weaknesses.'

Speaking ahead of the election, he claimed he would be 'more aggressive and more effective' than al-Assad on economic, administrative and social issues.

But on the overarching question of the war, al-Nouri offers no dissent.

'Politically, I think he's doing what he has to do,' he said.

Rebels divided

What al-Assad is doing is continuing the brutal offensive against those opposed to his regime, raining down barrel bombs on rebel-controlled parts of cities such as Aleppo and Deraa.

The opposition groups fighting against him are divided, with squabbling between factions and jihadis who have flocked from around the world to try to establish an Islamic state.

The rebels have lost ground around Damascus and Homs, and are under pressure in Aleppo and the south of the country.

Talks earlier this year mediated by the United Nations did little to change the situation, ending with the regime and the opposition firmly opposed.

Ban's office has warned that the elections are likely to worsen the situation, saying they 'will damage the political process and hamper the prospects for political solution that the country so urgently needs.'

If al-Assad emerges victorious, as expected, it will further diminish the likelihood of his stepping down anytime soon. The Syrian opposition and Western countries insist that al-Assad can't be part of any body that, under an agreement signed in Geneva earlier this year, would lead the country through a transitional period.

READ: U.S.: Jihadi featured in suicide bombing video in Syria grew up in FloridaREAD: Evacuation truce in key Syrian city of Homs goes into effectREAD: CNN Exclusive: Videos show brutality of radical group ISIS in Syria

CNN's Fred Pleitgen reported from Damascus, and Jethro Mullen reported and wrote from Hong Kong. CNN's Ben Wedeman contributed to this report.