After acrimonious verbal duels with President Hamid Karzai, top Obama administration officials threw their full weight behind the Afghan leader, using a number of Sunday television appearances on Sunday to describe the him as a strong and vital American ally. In an interview on ABC's "This Week," Defence Secretary Robert Gates said Karzai had a close working relationship with U.S. General Stanley McChrystal, the top NATO commander in Afghanistan, and was helping to plan the large-scale military campaign in Kandahar that is scheduled for later this year. "Gen. McChrystal feels that this is a man he can work easily with," Gates said. "We frankly have to be sensitive in our own comments about President Karzai in terms of being mindful that he is the embodiment of sovereignty for Afghanistan." The comments from Gates and Secretary of State Hillary Clinton represented the administration's latest efforts to ease tensions with Karzai after a series of increasingly tense exchanges between the two governments. The White House had for months publicly criticized Karzai for failing to take strong steps to battle corruption pervading the Afghan government. The criticism encouraged other politicians and media to go after Karzai, who was even called a drug-addict. But senior administration officials now believe that the approach may have backfired, by pushing Karzai into a corner and making him feel that he had no choice but to lash back at the U.S. The Afghan president, whose government is propped up by billions of dollars in foreign aid and the presence of more than 100,000 NATO troops, has in recent days charged the U.S. and its allies with meddling in Afghanistan's internal affairs and occupying his country. In a recent meeting with Afghan lawmakers, he threatened to join the Taliban himself if Western behavior didn't change, according to US media reports. In the wake of such comments, administration officials suggested that the U.S. might cancel Karzai's planned visit to Washington next month. On Sunday, however, Ms. Clinton said the trip would go ahead as scheduled. "We are looking forward to his visit," she told CBS's "Face the Nation." Ms. Clinton also pushed back against questions about Mr. Karzai's emotional state, continuing a recent administration push to adopt a softer line towards Karzai and to speak more warmly about the Afghan leader. Peter Galbraith, an American official who was fired from a top United Nations post in Kabul after criticizing Afghanistan's flawed presidential elections, said last week that Karzai was mentally unbalanced and suggested that the Afghan leader was using illicit drugs. Ms. Clinton, the nation's top diplomat, said such claims were false and stressed that Mr. Karzai was under enormous pressure. "I have to say some of these outlandish claims that are being made and accusations that are being hurled are really unfortunate," she said. Gates called Galbraith's remark about Karzai "stupid"