KABUL (Reuters) - Washingtons decision to begin withdrawing troops from Afghanistan in mid-2011 is wrong and the US president should make clear any reduction would be dictated by conditions, US Senator John McCain said on Wednesday. Gains by opposition Republicans in US congressional elections last week have raised questions of a possible revision of president Barack Obamas contested policy of starting to withdraw from the 9-year-old war in July 2011. US Defense Secretary Robert Gates suggested on Sunday in Australia the pace of the drawdown may not be entirely decided until shortly before it begins. It is wrong to set the date of July of mid-2011, it sends the wrong message and it created a problem, McCain told a news conference while on a congressional visit to Afghanistan. We need to have the president of the United States state unequivocally that it will be solely conditions-based. Obama ordered 30,000 extra troops to Afghanistan in December to try and turn the tide of the war, but said he would start pulling troops out from the middle of 2011 as security responsibility in some areas was handed to Afghans. McCain, Obamas 2008 presidential rival, said he was very pleased with military progress in Afghanistan over the past six months and that clearing operations had only been possible because of the additional troops. Setting the 2011 date would only encourage the militants, he said. I worry a great deal about the effect, not only here, but it encourages our enemies and it discourages our friends. Violence in Afghanistan is at its worst since the Taliban were overthrown by US-backed Afghan forces in late 2001, with record casualties on all sides of the conflict. NATO allies are expected to endorse a plan at a Lisbon summit this month to start transferring security responsibility to Afghan forces from next year, part of an ambitious Afghanistan strategy to hand over control of the whole country in 2014. The reduction of US troops will largely depend on the success in handing security over to Afghan forces in the country. Transition to Afghans is expected to begin in parts of the north and west.