Republicans don't know if they'll lose big or small on Tuesday, but they're already bracing for an epic blame game.Why it matters: Privately, Republicans acknowledge it's not a complicated version of Clue. The leading suspect: Mr. President, in the Oval Office, with an assortment of weapons — and one war.Returning Republican senators are unlikely to blame President Trump publicly. There's a price for that. And don't expect Trump to shoulder the responsibility.But do expect departing GOP lawmakers to take shots at Trump or his team, and Trump to fire back at Senate Republicans, whom he's never been shy about torching.The irony of Trump's second midterm: With Republicans privately resigned to losing the House, Trump can still credibly claim victory if they hold the Senate."It's Donald Trump's midterms. He gets all the credit if we win. He gets all the credit if we lose," one national GOP strategist told Axios.The Iran war: From Alaska to Maine, Trump's decision to go to war with Iran — and the resulting spike in gas and diesel prices — has become a major political liability for Republican Senate nominees."It's not tariffs … it's the war, it's gas prices, it's diesel," Texas Attorney General Ken Paxton...