WASHINGTON (Reuters) Richard Holbrooke, the top US envoy for Afghanistan and Pakistan, sought on Wednesday to allay growing concerns in Congress over the course of the war, saying the task is difficult but can succeed. At a hearing on oversight of billions of taxpayer dollars spent in Afghanistan, lawmakers listed concerns from specific cases of corruption to the most basic question of whether the nine-year-old war can be won. Do you really believe that we can succeed at this? Democratic Representative Ben Chandler asked Holbr-ooke. I think we really have to ask ourselves serious questions about whether or not this really is doable. Holbrooke, who helped broker peace in Bosnia, conceded that fighting a resurgent Taliban and helping to rebuild Afghanistan were massive tasks but he repeatedly defended the Obama administrations strategy. So yes, of course, I believe we can succeed. But it is difficult. And it is the most difficult job Ive had in my career, he said. Number one, on a personal note, I wo-uldnt be in this job if I thought it was impossible to succeed. Were not delusional, he added, listing problems from high illiteracy to trying to help Afghanistans government be accountable to its own people. Using large charts, USAID director Rajiv Shah and Holbrooke listed safeguards the Obama Administration and Afghan government were putting in place to help curb corruption, which Holbrooke said was the number one recruiting tool for the Taliban. Representative Kay Gran-ger, the top Republican on the subcommittee, said she was concerned by the new app-roach of funnelling more funds directly through the Afghan government. The ongoing allegations of corruption and illicit activity do not give me confidence that now is the time to subject US funds to unnecessary risk, Granger said. The hearing came just days after whistle-blowing website WikiLeaks made public more than 75,000 classified US military reports covering a range of incidents in the Afghan war. Holbrooke said the leak was pretty appalling but did not think there was anything in them that should change peoples views of both Afghanistan and Pakistan.