President Trump’s decision to launch a war against Iran without congressional signoff has splintered lawmakers, largely along party lines, and supercharged the debate over war powers authority. While most Republicans largely rallied around Trump’s decision to carry out the massive joint attack with Israel, Democrats quickly denounced the attack as an illegal “war of choice” and demanded Congress come back to Washington to take a vote on whether to authorize another Middle East invasion. Democratic leaders have vowed to forge ahead with their plans to force a vote on a war powers resolution next week in the House that would...