There is a growing consensus after South Carolina that Donald Trump may well get the Republican nomination. One key piece of evidence (besides his electoral victories): Jeb Bush, scion and pillar of the traditional wing and Trump’s most outspoken foe, went down to ignominious defeat; Republican voters are rejecting their party’s establishment in droves. Why is that?

Based on statements by Trump supporters, he is the only one standing up for them, expressing their feelings. They have lots of anger, lots of grievances. But above all, there is a sense that the deck is stacked against them in so many ways: by the rich, by ineffectual politicians, by immigrants supported by liberals. An article in the Christian Science monitor quoted South Carolinians on why they supported a New York businessman. Dianne Lawson of Ridgeland, S.C. explained, “He says what a lot of us want to say but are afraid to say.” Look at how Trump is wildly cheered when he rails against businesses that send American jobs offshore, and vows to block these Republican stalwarts; it is one of his biggest applause lines. This is not in front of Democrats, but with Republican voters in every state he has campaigned in.

Yet how has the Republican establishment responded to this deep and widespread outrage on the part of their constituents? More than any other concept, for a number of years, the Republican Party has stressed one idea as the single solution to the problems of this nation: cut taxes, especially on the rich. No job training, no infrastructure projects, nothing for those misfiiting to the new economy. It is this disconnect between the pain of Republican voters and leadership’s response that provided Donald Trump his opening, which the mogul then drove a truck though. Why this shortsightedness, this narrowness, that explains so much? You can thank Grover Norquist.

In 1985 Norquist founded Americans for Tax Reform, a taxpayer advocacy group whose founding principle is “a system in which taxes are simpler, flatter, more visible, and lower than they are today.” Their foremost accomplishment is the “Taxpayer Protection Pledge,” which asks candidates for federal and state office to commit themselves in writing to oppose all tax increases. Before the November 2012 election, 238 of 242 House Republicans and 41 out of 47 Senate Republicans signed on, making it the fundamental platform of the Republican Party, almost unanimously. An August 2015 article in the Washington Post bore the title, “Nearly All the GOP Candidates Bow Down to Grover Norquist.”

There was enormous danger here, and not for the obvious reason that tax policy is far more complex than a single simple solution. The real threat to the Republican Party was that by focusing on this one item, it failed to develop a full panoply of solutions (some of which, but not all, required public monies), failed to develop a national platform with a wide range of proposals. Going into this election cycle they still campaigned too much on the tax package, not enough on responses to the legitimate anguish so many of their voters were experiencing.

But one man did see the need, and produced a range of answers, on every aspect of American life today. Republican voters responded with vigor, and Donald Trump may well be their standard bearer this fall. Party leaders can thank Grove Norquist if that happens.