One year ago, Donald Trump began his elevator ride to infamy, with a pitstop at a lectern, where he accused Mexico of sending rapists into America and announced his candidacy for president of the United States. That rambling, xenophobic performance helped him solidify, almost overnight, a substantial base of support within a Republican electorate that otherwise didn’t care for him. As the months wore on, fueled by appreciation for his willingness and liberty to speak his mind—if not for his actual bigotry—the ranks of his supporters grew, and eventually became large enough to secure him the GOP presidential nomination.

This abbreviated, unconventional origin story helps explain Trump’s continued difficulty leading the Republican Party now that the primary has given way to the general election. Trump should have gained a predictable benefit from securing his party’s nomination long before Hillary Clinton clinched hers—a window of opportunity to identify divisions in the other party and exploit them. Trump, instead, proceeded to deepen divisions between Republican voters and the incumbents who already represent them.

Depending on your perspective, this has always been Trump’s immediate political threat or promise—that he might strip bare the pretense that high-minded, philosophical conservatism, rather than ethno-nationalist grievances, are what drives Republican politics. His dumbfounding response to the massacre in Orlando exemplified his potential to break the GOP, but it was only the latest indication.

Trump has convinced the vast majority of Republican voters to fall in line behind him, and thus behind a political persona and policy agenda that are orthogonal to the party establishment’s conception of itself. He has the power; they are stuck with him; but it is an exceedingly poor fit, and the relationship between the two seems fatally unstable.

Most Republican leaders expected (or hoped or prayed) that, once victorious, Trump would move in their direction, if not substantively then at least temperamentally. But those Republicans were essentially asking Trump to abandon the qualities that drove his early political success and swap them out for qualities that in his mind define the losing candidates in the primary he won, and the Republican nominees whom Barack Obama defeated handily. This would be the right way of thinking if Trumpism had a wide general-election consistency.

But Trump has lost the plot. He is following instincts that are serving him poorly. Republicans would be perfectly happy with Trump if his rhetoric and policies divided Democrats from one another, even if in deploying wedge issues, he occasionally veered from GOP orthodoxy. Instead, he is uniting the Democratic coalition faster than Hillary Clinton could have hoped, and tearing his own party apart.

The term “wedge issue” first came to prominence in the 1990s as a catch-all to describe substantive ideas that exploited tensions within opposing coalitions. Its precise etymology is unclear, but in 1986, the Washington Post columnist David Broder wrote of a Republican congressman’s efforts to “find an issue that would drive a wedge into … the ‘unnatural’ and ‘unstable’ Democratic coalition” of blacks and poor whites. Four years later the words appeared in the New Republic for the first time, when Sidney Blumenthal recounted a meeting of “the political directorate of the Republican Party,” convened shortly after the inauguration of President George H.W. Bush, to “agree on a ‘wedge issue’ they could drive into the Democratic Party and further divide it.”

In September 1992, accepting credit for a coinage that wasn’t his, former Jimmy Carter adviser Stuart Eizenstat told The New York Times’ William Safire, “I was looking for a phrase to illustrate the attempt to split the coalition of working-class whites and blacks, the two constituencies Roosevelt unified on economic grounds. The image came to mind of a wedge being driven.”

Every political coalition is riven by tensions and weaknesses, and a wedge issue serves, as the metaphor suggests, to pry factions of the opposition apart from one another. The wedge is one of the most basic, important concepts in modern politics, and the idea that it’s a tool one party uses against another resides at its core.

Donald Trump is not the first major-party nominee in modern history to make his co-partisans uneasy. But he is the first to take wedge issues and turn them inward.

During the George W. Bush administration, and on occasion in the Obama years, the GOP used “tough on terror” policies as wedge issues to divide dovish Democrats from hawkish or politically squeamish ones. Earlier in Trump’s candidacy, liberals and anti-Trump conservatives worried that he might do the same—that a mass-casualty act of terrorism days or weeks before the election could propel Trump to a victory that would’ve otherwise been out of reach. (Republican Trump supporters, rather disgustingly, make the same calculation.)

The killings in Orlando have turned that analysis on its head. The attack prompted Trump to restate and expand his call for a Muslim travel ban, and to reprise a campaign of incitement against American Muslims whom he claims harbor terrorists and knowledge of their plots. This was a strategically poor time for Trump to reach back to nativist shibboleths of any kind. But he specifically picked two that have been condemned roundly by the Republican Party leadership, and that strengthen the Democratic coalition’s opposition to him.

In multiple venues since Sunday, Trump has presented himself as an LGBT ally who will protect gays and lesbians from murderous Islamists better than their false friend Hillary Clinton. “[She] can never claim to be a friend of the gay community as long as she continues to support immigration policies that bring Islamic extremists into our country and who suppress women, gays and anyone else who doesn’t share their views or values,” he said in his official response to Orlando on Monday.

In essence, Trump is trying to use terrorism not as a wedge between national-security factions of the Democratic Party, but between the Democratic Party and the community that was the target of the Orlando massacre. Setting aside the obvious, ghoulish cynicism, this plays victims of homophobia for fools who can’t see that Trump’s coalition is home to David Duke, Louis Farrakhan, and Jerry Falwell, Jr., not to defenders of LGBT equality.

His impulsive decision to align, however temporarily, with Democrats on the question of whether people on the “no fly” list should be allowed to buy guns, was an attempt to use anti-terror politics to wedge certain gun control supporters out of the Democratic coalition. Instead, it made conservatives shudder. These are not wedges that will divide Democrats. They’re wedges that will divide Republicans.

The effects of this are evident to every reporter on Capitol Hill who has tried to ask leading Republicans about Trump’s response to Orlando this week. Rather than working with their presidential nominee to wrong-foot Democrats, they’re struggling to find any sense of balance themselves. “I’m not going to be commenting on the presidential candidate today,” said a visibly uncomfortable Senate Majority Leader Mitch McConnell at his weekly press stakeout Tuesday, pointedly refusing to even say the word “Trump.” The initial polling after Orlando shows the public responding positively to President Obama and Hillary Clinton and recoiling in horror from Trump. Only half of Republicans approve of his response.

Everything we know about Trump tells us he is incapable of and uninterested in the pivot Republican leaders want him to make. He is much likelier to keep wedging and wedging away at ambivalent or reluctant supporters until all that’s left are his core fans. The question is whether Republicans in Congress will eventually despair of the presidency and rescind their endorsements, or whether the GOP will become, in a much more literal sense, the Party of Trump.

Want to hear more about Trump, wedge issues, and the Republican Party? We recommend this episode of our Primary Concerns podcast, hosted by Brian Beutler: