Diving gleefully off script at a campaign event on Tuesday night in Nashville, Donald Trump picked up right where he left off earlier this month, calling members of the Salvadoran-American street gang MS-13 less than human. “They’re not human beings,” he declared. “And this is why we call the bloodthirsty MS-13 gang members exactly the name I used last week. What was the name?” he asked the crowd, which responded with a booming chant of “Animals!” This is what “rallying the base” looks like in 2018, as the midterm elections approach. Trump was in town to churn up excitement for Republican congresswoman Marsha Blackburn in the battle for Bob Corker’s newly open Senate seat against Democrat Phil Bredesen, a former Tennessee governor. It was also, in a way, a metaphor for the state of play in Washington as Republicans brace for what could be a blue wave in November. Not only did Trump employ his patented method of belittling opponents (“I never heard of this guy. Who is he?” he asked of Bredesen), but he leaned further into a brand of Trumpian paranoia and toxicity that’s come to define his midterm-campaign efforts.

Xenophobia, which Trump wielded like a cudgel in 2016, is once again leading the G.O.P. playbook. ”They make all of this money,” Trump said of the Mexican government, “and they do absolutely nothing to stop people from going through Mexico from Honduras and all these other countries—the caravan, all of this stuff—they do nothing to help us. Nothing.” At one point, he claimed that House Minority Leader Nancy Pelosi “loves MS-13,” and he tied Bredesen to the rest of the Democratic cabal loathed among his base. “If Bredesen were ever to get elected, he would do whatever Chuck [Schumer] and Nancy [told him],“ he said. “They don’t want the wall; they want open borders. They’re more interested in taking care of criminals than they are of taking care of you. Bredesen donated a lot of money to the campaigns of Barack Obama and Hillary Clinton,” he added, throwing in a “Crooked Hillary” for good measure, and encouraging a round of “lock her up” chants.

The Deep State conspiracies, however, are a newer addition to Trump’s campaign playbook. In the absence of any definitive G.O.P. agenda for the current legislative calendar, Trump’s rants about the F.B.I., D.N.C., Tony Podesta, and the Clintons have become a default strategy of their own. Even among more moderate Republicans, who are tiptoeing around the president, his fulminations are inescapable. The Republican Party, under Trump, has become the party of Alex Jones. And in some right-leaning districts, the culture war is working. In response to the unprecedented wave of energy sweeping through the Democratic camp, in particular among women and people of color, Trump is having some success dialing up the outrage machine to electrify his base. “Taxes. Pelosi. Immigration. These are red-meat issues,” one person involved in Trump’s re-election effort told Politico. Similarly, the president is counting on Robert Mueller’s Russia investigation to whip Republican voters into a frenzy. “I have no reason to believe that wouldn’t work to keep control of the Senate for sure and the House probably,” said Trump lawyer Rudy Giuliani, referring to Trump’s dire hints that he will be wrongfully impeached should the G.O.P. suffer a midterm rout. (So far, it has worked: 6 in 10 Republicans now believe Mueller’s probe is unfair, according to an April poll.)

The message won’t work everywhere, particularly in some purple districts where Trump-weary moderate Republicans are becoming independents in droves. But G.O.P. operatives are betting that a surgical approach will allow them to hold the Senate. As The New York Times notes, the second part of Trump’s dual-pronged strategy will consist of attacking Democrats who are close to defeating G.O.P. incumbents, as well as Democratic incumbents in states Trump won by large margins in 2016. Speaking to the Times, Republican strategists noted that with their one-seat majority in the Senate (and, implicitly, their assortment of weak seats in the House), it will be crucial to deploy Trump to put red-state Democrats, torn between the demands of their party, their anti-Trump base, and their Trump-supporting constituents, on the defensive. “He’s the definer in chief,” Rob Collins, who ran the National Republican Senatorial Committee in 2014, told the Times, referring to one of Trump’s most effective offensive strategies. “He comes in, defines the opponent in a way that’s unconventional and unorthodox, but it sticks.” Even Josh Holmes, a former top adviser to Mitch McConnell and an on-again, off-again critic of the president, acknowledged that Trump “can strip bark more than anybody I’ve seen . . . And the bang for your buck you get out of these visits is like 10 to 1 what any other president can do. Imagine the local news station doing something else for the first 15 minutes of the broadcast if Trump is in town.”

Bombarded by the barrage that’s sure to increase as midterms approach, the playing field itself may be destroyed. “The president of the United States would rather you believe that there is domestic meddling in the next U.S. elections (with no evidence), than there was Russian meddling in the last one (despite incontrovertible evidence),” Mo Elleithee, a longtime Democratic strategist, told Politico. “His disrespect for our democracy is stunning.” But the true test of Trump’s strategy will be whether it ultimately dings the very candidates he’s trying to bolster. So far, special-election candidates who have attempted to follow the Trump playbook have come away empty-handed. What’s less clear is whether it will prove effective with the man himself back at the helm.