It’s been just four days since the president learned that Robert Mueller found no evidence of collusion, but Rudy Giuliani, Donald Trump’s lawyer, is no longer in the mood to celebrate. He’s thrilled about the outcome, of course, as is his client. Trump told the former New York mayor that “he’s happier than he thought he would be.” But Giuliani, sipping a Diet Coke on Wednesday morning at the Trump Hotel, said it’s time to focus on the next mission: Find out who started all this—and why. “We’re now trying to prove who did it,” Giuliani said. “The premise is, somebody had to have started the ‘He colluded with the Russians’” narrative. (Never mind that Trump’s posture toward the Kremlin has long been strange.) Asked whether the president himself wants an investigation to examine this question, Giuliani said, “Goddamn right he [does]. This is not ‘Oh, gee, it’s over, let’s forget about it.’” A reliable barometer of Trump’s moods, Giuliani offered a glimpse into the future. Mueller might be done with his investigation, but Trump and company are loath to let it drop. They want to capitalize on the president escaping criminal charges and make Mueller’s findings a core piece of 2020 campaign messaging. In their view, Attorney General William Barr’s four-page summary of the report is a gift that vindicates Trump, undercuts Democratic investigations, and repudiates critical news coverage. There’s time enough to talk policy on the campaign trail. Team Trump first wants to showcase the special counsel’s conclusions: According to Barr, Mueller reported no evidence that the Trump campaign colluded with the Russians, and he couldn’t make a judgment on obstruction of justice. Even though the probe has led to 215 criminal charges and five prison sentences, Trump and his allies have framed Mueller’s findings as total exoneration. Yet many Republican lawmakers and strategists fear that Trump would be fixating on the wrong message at the wrong time. They worry that Trump risks repeating the same strategic blunder he made in the midterm elections, which culminated in Republicans losing control of the House. Rather than spotlight economic gains rung up on his watch, the president might wind up dwelling on collateral issues of scant interest to voters. In the midterms, Trump locked onto migrant caravans making their way north from Mexico, warning of a national-security threat that never materialized, and ultimately made little mention of the bread-and-butter issues that some strategists believe would have bolstered his party’s odds for winning. Tensions over Trump’s campaign message underscore a split within the Republican Party that’s existed since the day he announced his candidacy for president in 2015. Then and now, he’s trampled long-held convictions about how a presidential candidate should behave, relying on his own instincts and feel for the voters’ mood, to the dismay of mainstream GOP figures. Though the establishment and Trump wings of the GOP have joined forces since the 2016 campaign, the next election will test their alliance anew, with the Mueller report emerging as an early flash point. Trump allies see Barr’s letter as a kind of Swiss Army knife—a tool useful in all kinds of situations. Not only is it exculpatory, they say, but it also implicitly rebukes the press for its coverage of the Russia investigation, inoculating Trump from any future scandal that reporters might unearth. According to a source familiar with internal discussions at the Republican National Committee and the pro-Trump super PAC America First, both organizations are “geared up for any nonsense to come.” They’re already prepared to attack reporters. “Any reporter who tries that will be hit with 30-second spots of all their ridiculous claims about collusion,” said the source, who,