Barack Obama's arrival in the White House and the wind of change sweeping through Washington could lead to the ousting from power of Hamid Karzai, President of Afghanistan, The Independent has learnt.

International support for Mr Karzai, who was once the darling of the West, has waned spectacularly, amid worsening violence, endemic corruption and weak leadership. But until very recently, diplomats insisted there were no viable alternatives even as fighting has intensified and the Taliban insurgency in the south has grown. But four key figures believed to be challenging Mr Karzai have arrived in Washington for meetings with Obama administration officials this week. There is now talk of a "dream ticket" that would see the main challengers run together to unite the country's various ethnic groups and wrest control away from Mr Karzai.

"The Americans aren't going to determine the outcome of the election, but they could suggest to people they put their differences aside and form a dream ticket," said a senior US analyst in Kabul.

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Mr Obama has already started getting to grips with the challenge of Afghanistan; he received a briefing on the coming American troop "surge" from General David Petraeus on Wednesday, his first full day in the Oval Office. Last night, Mr Obama appointed the veteran US diplomat, Richard Holbrooke, as his new special envoy for Afghanistan and Pakistan.

The unofficial delegation to Washington was made up of three ex-ministers and a serving governor. Dr Abdullah Abdullah was the foreign minister, Dr Ashraf Ghani served as finance minister, Ali Ahmad Jalali was interior minister and Gul Agha Sherzai is the governor of the eastern province of Nangahar, where US troops are based. When Mr Obama visited Afghanistan in July he met Governor Sherzai in Jalalabad, even before he saw President Karzai in Kabul. "They are not going to blindly back President Karzai like the Bush administration did for so long," said John Dempsey, head of the United States Institute of Peace in Kabul. On the ground in Afghanistan, Camp Bastion in Helmand province is already becoming the symbol of the Americanisation of the war in the south. US forces have started arriving and will be joined by many more. Airfields are to be built to bring in transport and warplanes in preparation for a coming offensive with the dispatch of 30,000 additional troops to Afghanistan.

Karzai officials had hoped Hillary Clinton, now the US Secretary of State, would prove their ally in White House. But those hopes were dashed last week when she branded Afghanistan a "narco-state" with a government "plagued by limited capacity and widespread corruption" during her confirmation hearing.

Ahmed Wali Karzai, the Afghan president's brother, was named last October in leaked US intelligence reports as a major narco-trafficker. The allegations, vigorously denied by both men, are widespread in Afghanistan but, until then, Western officials had refused to corroborate them. But the leak was seen as a shot across Mr Karzai's bows from the Bush administration, to make him clean up his act and rein in his brother. The flurry of criticism suggests the international community is less than happy with his response. Mrs Clinton's remarks coincided with stinging criticism from Nato's secretary general, Jaap de Hoop Scheffer, who said corrupt and inefficient government was as much to blame for instability as the insurgents. Writing in The Washington Post, he said: "The basic problem in Afghanistan is not too much Taliban; it's too little good governance."

Individually, Mr Karzai's rivals risk splitting their support base. Together, diplomats are optimistic they could win the election, expected next summer, and reinvigorate a jaded population. "We need to create a new momentum, like in 2001," said Haroun Mir, co-founder of the Afghanistan Centre for Research and Policy Studies. "Change will bring hope, because right now the momentum is with the Taliban."

The planning for new policies on Afghanistan has been going on for months by Pentagon and State Department staff in anticipation of Mr Obama's inauguration. One official said: "We have to come up with fresh innovative ideas on counter-insurgency, counter-narcotics, governance, development. Now they are drafting in people from other departments. There is no doubt we neglected Afghanistan after the Taliban fell but there is a worry that we may be trying to do too much, too fast now."

A slew of initiatives are on the way. They include the arming of local groups to fight the Taliban, in the way Sunni militias were used against insurgents by General Petraeus in Iraq.

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US, British and Nato forces will also play a much more direct role in counter-narcotics operations in an effort to tackle Afghanistan's heroin trade which provides 93 per cent of the world's supply of the drug.

Some policy analysts insist it is impossible to blame the Afghan president for all his country's ills. They say the international community has been ineffective, often divided and international military effort was focused on catching terrorists, not quelling an insurgency for far too long.

British anger at Taliban patients

British soldiers complain that they are being forced to share hospital facilities in Afghanistan with Taliban fighters. Enemy combatants are treated at the Camp Bastion Field Hospital in line with the Geneva Convention. But personnel are objecting to the traditional war-time practice. "My friends... were waking up in the hospital to find Taliban in the bed next to them," one soldier said. "The last thing they want to see when they come round is the Taliban on the same ward. It's just not right."

The Ministry of Defence said it had not received any complaints.

The challengers: Who might replace Karzai?

Gul Agha Sherzai

A veteran of the wars against the Soviets, Mr Sherzai (whose name means "son of a lion") is a former governor of Kandahar criticised for human rights abuses. He escaped assassination in 2006.

Dr Abdullah Abdullah

Although half Pashtun, he is considered a leader of Afghanistan's Tajik population. He was appointed Minister of Foreign Affairs in 2001 and served until 2006.

Ali Ahmad Jalali

An ethnic Pashtun and former colonel, Jalali joined the anti-Soviet resistance after the Russians invaded Afghanistan in 1979. He took US citizenship and spent 20 years broadcasting for Voice of America.

Dr Ashraf Ghani

An ethnic Pashtun, he studied in America, at Colombia University. He worked at the World Bank from 1991 to 2001, when he returned to Afghanistan for the first time in 24 years. From 2002-04 he was Finance Minister and oversaw the successful transition to Afghanistan's new currency.