Calls are growing from within the Liberal caucus for Prime Minister Justin Trudeau to step down as party leader — and some have pegged Chrystia Freeland as their choice to replace him.Twenty-one Liberal MPs have publicly urged Trudeau to resign — many of them within the last week — after Freeland shocked Canadians on Monday by resigning as deputy prime minister and finance minister hours before she was supposed to table the government's fall economic statement.