HERAT, Afghanistan — When Dr. Abdullah Abdullah, the main election challenger to President Hamid Karzai, arrived here to campaign last weekend, thousands of supporters choked the six-mile drive from the airport. Cars were plastered with his posters. Motorbikes flew blue banners. Young men wearing T-shirts emblazoned with his face leapt aboard his car to embrace him to ecstatic cheers.
With only a month to go, Dr. Abdullah has started his campaign late, but in its first two weeks he has canvassed six provinces and drawn growing support and larger crowds than expected. Rapturous welcomes like this one have suddenly elevated him to the status of potential future president.
“I have no doubt that people want change,” Dr. Abdullah said in an interview after a tumultuous day campaigning in Herat, in western Afghanistan, adding that his momentum was just building. “Today they are hopeful that change can come.”
Mr. Karzai is still widely considered the front-runner in the campaign for the Aug. 20 presidential election. But Dr. Abdullah, who has the backing of the largest opposition group, the National Front, is the one candidate among the field of 41 who has a chance of forcing Mr. Karzai into a runoff, a contest between the top two vote-getters if no candidate wins more than 50 percent of the votes in the first balloting.
Already well known among most Afghans, Dr. Abdullah, 48, an ophthalmologist, has a background that includes years of resistance to Soviet and Taliban rule as well as a crucial role in the formation of the new democratic government after the American intervention.
A dapper dresser, wearing traditional Afghan clothes under a variety of Western tailored jackets, he combines solidarity with the former resistance fighters with the moderation of the Afghan intellectual, giving him potentially broad appeal.
After serving as foreign minister in Mr. Karzai’s government for five years, he left in 2006 and has since become a strong critic of the president’s leadership. He refused an offer to become Mr. Karzai’s running mate, and he contends that the president practices a policy of divide and rule that has polarized the country.
Today, Dr. Abdullah, with a diplomat and a surgeon as his running mates, is seen as part of a younger generation of Afghans keen to move away from the nation’s reliance on warlords and older mujahedeen leaders and to clean up and recast the practice of governing.
To do that, he advocates the devolution of power from the strong presidency built up under Mr. Karzai to a parliamentary system that he says will be more representative. He is also calling for a system of electing officials for Afghanistan’s 34 provinces and nearly 400 districts as a way to build support for the government.
Those provincial governors are now appointed from Kabul, and many have been criticized for cronyism and corruption. Influential Shiite clerics here in Herat, who supported Mr. Karzai in the last election in 2004, are now so fed up with corrupt appointees that they have said they will back Dr. Abdullah this time.
Re-engaging the people is essential to reverse the lawlessness and insecurity that have reached a critical point in much of the country, Dr. Abdullah said. “They have managed to lose the people,” he said of the current government. “In fighting an insurgency, you lose the people and you lose the war.”
Before several thousand people in Herat’s sports stadium, he raised the biggest cheer with his promise to build up Afghan institutions so that foreign troops could go home soon.
He also promised to curb the rampant corruption and review foreign assistance programs to ensure that they focused on grass-roots development and addressed poverty and unemployment. In his public meetings, he emphasized support for the rights of women, the unemployed, the disabled and the victims of war.
He said he would work seriously toward reconciliation with the Taliban, calling the current process a “joke.” Yet in an interview he retained his longtime opposition to the Taliban leadership and said he doubted that the Taliban leader, Mullah Muhammad Omar, was ready to negotiate for peace.
This is only the second national presidential election in Afghanistan’s history, and political analysts warn that it is virtually impossible to predict how the election will go or to read voters’ intentions. Diplomats calculating the numbers of the various factions that have come out in support of Mr. Karzai say that he will just scrape back in, thanks largely to the support from the largest ethnic group, his fellow Pashtuns.
Yet two opinion polls conducted this year suggested that Mr. Karzai had lost considerable support since his 2004 victory with 55 percent of the vote. One of those polls, conducted in May by the International Republican Institute, a nonprofit pro-democracy group, showed that Mr. Karzai’s support was down to 31 percent. While only 7 percent said they would vote for Dr. Abdullah, the poll indicated that the election would have to go to a second round.
People interviewed in Herat also spoke of a shift in the public mood. “Karzai has governed for eight years and all the problems have increased, not decreased,” said Hosseini, 47, a farmer who uses one name and who traveled to the city to hear Dr. Abdullah speak.
Although Dr. Abdullah has significant support in the north and the large population centers, he will have difficulty campaigning in the south, where the insurgency makes movement virtually impossible.
And although he may tap into the desire for change after nearly eight years of Mr. Karzai’s rule, supporters and analysts say Mr. Karzai will still dominate in his Pashtun homeland in Kandahar, in the south.
Dr. Abdullah also claims heritage from Kandahar through his father, Ghulam Muhayuddine Khan, a Pashtun who was a senator in the 1970s. Yet he is far better known for his connection to the northern Panjshir Valley, through his mother and his close relationship with the famous resistance commander Ahmed Shah Massoud, who fought both the Russian occupation and the Taliban.
Dr. Abdullah dismissed suggestions that he could not raise support in the Pashtun south and said that support for Mr. Karzai in the area had dropped drastically as security had worsened and more people had joined the insurgency. “Southern Afghanistan has nearly announced jihad against Karzai,” he said.