President Donald Trump’s policies and personal conduct regularly generate fierce backlash from his political adversaries. But over the last two months, fresh counterblasts are coming from an unexpected quarter: his allies. Three House Republicans joined Democrats on Tuesday on a rare procedural vote to rebuke the president and GOP leadership, which paved the way for more GOP lawmakers to vote for a resolution to block Trump’s Canada tariffs on Wednesday. The final head count of Republicans who backed that resolution as it was adopted, with mostly Democratic votes: six. A Republican governor who leads a national association representing governors of...