Syrians voted Wednesday in a presidential election whose outcome is not in doubt. Such is the extent of President Bashar al-Assad’s control over the electoral process that the poll is certain to deliver him a comfortable victory, a fourth seven-year term that will affirm his survival in the face of the 10-year-old rebellion against his rule.

The election also delivers a rebuke to a decade of Syria diplomacy by the United States and its allies aimed at securing a transition to democracy. By the time Assad’s new term ends in 2028, he will have been in power for 28 years, topping the 27 years his father, Hafez, served as president.

 In a powerfully symbolic gesture, Assad cast his vote in the destroyed Damascus suburb of Douma, the site of a 2018 chemical attack that the United Nations attributed to the Syrian government and that killed at least 40 people. Crowds of supporters chanted “Our souls, our blood for you, Bashar” as he arrived at the polling station with his wife, Asma.

The area was controlled by the rebels during the last election, in 2014, and the choice of venue underscored the sense of triumph accompanying the Assad campaign.

Among loyalists, there was a celebratory mood as the vote got underway, with some saying they are planning picnics and parties to mark the occasion.

“This is a message to the Western countries that tried to overthrow Syria,” said a reporter broadcasting live from a polling station in Hama province for the state-owned al-Ikhbariyah TV channel. “Now the people are choosing their own destiny.”

This election is the second to be held in the shadow of the Syrian war under the terms of a new constitution introduced in 2012 that allowed rival candidates to compete for the first time since the 1960s. It also left Assad as the ultimate arbiter of who may run and security services in charge of administering the poll, leaving little opportunity for real competition.

Two other candidates are running this time around, but they are unknown figures lacking constituencies. The overwhelming preponderance of Assad posters and billboards looming over the streets of Damascus and other Syrian cities speaks to the likely margin of his victory.

Election slogans supporting Assad adorned government ministries and the security agencies, dreaded by all Syrians for the torture they administer to those who express dissent — further underlining the message that Assad’s victory is guaranteed.

“No other choice,” said one of the banners strung outside the headquarters of the Air Force Intelligence Directorate, among the most dreaded of the security agencies.

A joint statement Tuesday by the United States, Britain, France, Germany and Italy denounced the election as “illegitimate.”

“Syria’s May 26 presidential election will be neither free nor fair,” the statement said. “This fraudulent election does not represent any progress towards a political settlement” to the war that lingers, 10 years on.

What it also represents, said Robert Ford, who served as U.S. ambassador to Syria during the earliest years of the anti-Assad rebellion, is the failure of U.S.-backed diplomacy aimed at bringing about a transition from Assad family rule through a U.N.-sponsored peace process in Geneva that has dragged on for seven years without result.

The Biden administration has shown little inclination to engage too deeply on Syria beyond expressions of support for efforts to deliver humanitarian aid. No special envoy has yet been appointed, and an interagency review of Syria policy has yet to produce results.

But it is unclear what the United States can do to influence the course of events in a country where Russia, Iran and Turkey have become the main power brokers, Ford said.

“This election shows that the Americans have no leverage. If they had leverage, Assad would not be able to hold this kind of campaign, with the full backing of his military and intelligence apparatus,” Ford said. “Great powers like the United States cannot remove this guy.”

The only question is by what margin it will be considered seemly for Assad to win, said Ibrahim Hamidi, a Syrian journalist with the regional Asharq al-Awsat newspaper. After securing in excess of 99 percent of the vote in his first two elections, Assad’s share fell to 88.7 percent in 2014, after a competitor was allowed.

In all that time, Assad “has not budged an inch, and he did not make any concession,” Hamidi said.

The election also draws attention to the huge challenges that remain. Though the worst of the fighting has subsided, two-thirds of the country remains out of Assad’s grasp, including the rebel-controlled northwestern province of Idlib and the expansive desert area of the northeast, where U.S. troops are still present, alongside Kurdish-led forces.

Voting is taking place only in the part of the country controlled by the government, where living conditions continue to deteriorate despite the winding down of the fighting. Electricity and fuel are in short supply. Vast areas have been destroyed. More than 90 percent of the population is living in poverty, according to the United Nations.

Hunger is mounting as the collapse of the currency puts basic staples beyond the reach of most ordinary people. Half a million children are chronically malnourished, the U.N. says, and Syria is one of a handful of countries identified as being at risk of famine this year. U.S. and European sanctions have deterred any significant investment in the massive effort of rebuilding the country’s destroyed infrastructure.

The election seems unlikely to deliver any respite from these daily hardships or any new direction in government policy. Some Syrians are griping about the cost of the election at a time when so many are struggling to survive, said a Damascus resident, who spoke on the condition of anonymity for fear of repercussions. “It’s just a show, and the people are poor,” he said.

Others said they hope the vote will bring new recognition of the inevitability of Assad’s survival and open the door to international aid and reconstruction funding, particularly from those Arab countries that severed relations after the 2011 uprising.

“People are optimistic because they hope foreign embassies will reopen and sanctions will end,” said another Damascus resident, who also spoke on the condition of anonymity.

Western diplomats say they see little likelihood that an election widely regarded as flawed in Western capitals will prompt steps toward normalizing relations with Assad. Although some Arab countries, notably the United Arab Emirates, have restored relations, important regional powers such as Egypt and Saudi Arabia have held back, deterred by sanctions and the lack of progress toward a political settlement that would resolve the larger crisis of a divided and impoverished Syria, the diplomats say.

Sly reported from London, Durgham from Beirut and Haidamous from Washington.

Correction: A previous version of this article misstated the margin of victory for President Bashar al-Assad in 2014. He won with 88.7 percent of the vote.