OTTAWA — Liberals and Conservatives joined forces Wednesday to block an NDP motion that threatened to trigger a fall election. The motion, at the Commons environment committee, called for the resignation of Environment Minister Rona Ambrose. If it had passed at committee, it would have gone to a vote in the House of Commons in the fall. And because the Conservatives declared it a confidence motion, it threatened to bring down the government. Even though Conservative committee chair Bob Mills had declared the motion valid, Tory members challenged his ruling and overturned it with the support of the Liberals. “The...