The NDP suffered a massive electoral blow in 2000, loosing all but two of their seats, one of which was MacPhail's. Shortly after, McPhail was elected as the party's new leader. She was a harsh critic of the new Liberal Party Premier Gordon Campbell, often fueled by the Premier's refusal to grant MacPhail the status of Leader of the Opposition on the basis of her party's small representation, despite the fact that she led the only other party in the legislature. MacPhail stepped down as leader in 2002 and was replaced by Carol James.
MacPhail is the great-grandaughter of Agnes MacPhail, the first woman ever elected to the Parliament of Canada.