Recent federal polls have shown a dramatic shift in Canadians' voting preferences, but analysts say there is no guarantee it's a lasting trend. CBC's Poll Tracker has clocked a massive Conservative lead for the better part of the last two years. But survey results from the past few weeks suggest that lead is quickly evaporating. An Ipsos poll conducted between Feb. 21 and 24 has the Liberals ahead of the Conservatives among decided voters — though the two-point spread falls well within the 3.8 per cent margin of error. Still, it's the first time Ipsos has shown the Liberals in...