MADISON, Wis – Opponents of Wisconsin Gov. Scott Walker said Tuesday they have obtained more than 1 million signatures on petitions to recall him from office, nearly half of the number that voted in the 2010 election that put him into office."It is beyond legal challenge,'' said Ryan Lawler, a vice-chairman of United Wisconsin, the main recall organization. It is also well beyond the 540,208 needed to trigger a recall election. The petitions are to be submitted to the Government Accountability Board, which will examine them to determine their validity.Assuming that happens – and Walker himself has said he expects a recall election – Walker's future would likely be determined in May or June. He would have to stand for election against an as yet undetermined Democratic challenger. Mike Tate, chairman of the state's Democratic party, said he expects several Democrats to enter the race, forcing a primary.The one million signatures represents "a crystal-clear indication of how strong the appetite is to stop the damage and turmoil that Scott Walker has brought to Wisconsin,'' said Lawler. Walker, a Republican, won 1.12 million votes in the 2010 election.The recall effort began last winter when Walker and the Republican-controlled Legislature unveiled a budget-balancing bill that greatly reduced public employees' power in negotiating contracts with state and local employers. That bill ultimately passed, and Lawler admitted that it remained the driving force for many of the estimated 30,000 volunteers who circulated petitions to force a recall election.