NAIROBI, Kenya — Two years ago, Kenyans ranked as the most optimistic people on Earth.

Residents of this East African nation had just voted out a corruption-riddled ruling party and replaced it with an opposition leader who promised to clean up government graft, boost the economy and approve a new constitution in his first 100 days.

Their exuberance spread to the West, where President Bush welcomed the new president, Mwai Kibaki, to the White House, anointing the country as one of Africa's most promising emerging democracies.

But after a strong start, Kibaki's administration has stalled. High hopes have turned to bitter cynicism. And it's not hard to find citizens who feel angry and betrayed.

"We were conned," Joseph Mwelesa, 32, said from behind the counter of his candy stand in Nairobi. "The [old] times were bad, but Kibaki is even worse."

Graft is so rampant, the nation's widely respected anti-corruption czar, John Githongo, quit in frustration in February, and the U.S. and German governments protested by suspending nearly $10 million in aid.

Western observers are concerned that Kibaki's government is displaying some of the same bad habits seen during the administration of President Daniel Arap Moi and appears unable or unwilling to address problems.

"We got suckered in, just like everyone else," said one Western diplomat who spoke on the condition of anonymity. "Some of the corruption began before this administration came into power, but the Kibaki folks slid right into the transactions and demanded their cut."

A deepening fracture in Kibaki's fragile coalition government has crippled parliament and delayed the constitution, spurring a leading coalition partner to call for mass anti-government protests.

To shore up his power, Kibaki turned to one of the previous government's most controversial power brokers, Nicholas Biwott, whose record and past dealings are so questionable that the United States refused to issue him a visa last year.

Kenya's leading newspapers run banner headlines daily about the latest government scandals, perpetuating the perception that even under the new government, Kenya's rich and powerful continue to live by their own set of rules.

Kibaki's unpredictable wife, Lucy, raised eyebrows this month after storming into a farewell party for her neighbor, the outgoing World Bank director, and ordering that the music be turned down because it was disturbing her sleep.

Newspapers plastered the story across their front pages and accused the first lady of abusing her position. Undeterred, the next day Lucy Kibaki swept into the downtown offices of a leading newspaper in the middle of the night — government security officers in tow — and chewed out journalists for hours, slapping a cameraman who took her picture. When the cameraman pressed assault charges, the attorney general ordered that the case be dropped.

The controversies are taking a toll. When Gallup polltakers returned to Kenya recently, they found the number of people who were optimistic about the future had plummeted to 41 percent from 77 percent in 2003.

"We are today at a very dangerous junction in this country," opposition leader Uhuru Kenyatta told Western business leaders last week. His own Kenya African National Union party was ejected by voters in 2002, after 40 years in power, over many of the same complaints now facing Kibaki's government.

The ever-smiling Kibaki has so far tried to steer clear of the controversies, allowing much of the criticism to fall on his aides.

During a speech before an International Press Institute conference in Nairobi last weekend, Kibaki defended his tenure and called Kenya "one of the most democratic countries in Africa and indeed the world. Since my government took over two years ago, we made a commitment to widen the democratic space."