In 2018, Laffer wrote the book "Trumponomics" with conservative economic commentator Stephen Moore, wherein they lauded the Trump administration's economic policies. In the book, Moore and Laffer argue that the Trump administration's 2017 tax plan would raise growth rates to as much as 6% and not increase budget deficits. In a 2019 review of the book, Greg Mankiw, a conservative economics professor at Harvard University, said the authors "do not build their analysis on the foundation of professional consensus or serious studies from peer-reviewed journals. . . . The Laffer curve is undeniable as a matter of economic theory. There is certainly some level of taxation at which cutting tax rates would be win-win. But few economists believe that tax rates in the United States have reached such heights in recent years; to the contrary, they are likely below the revenue-maximizing level." The one issue where Moore and Laffer disagree with Trump is on the issue of free trade, which the duo supports. Previously, in 2016, Laffer said that he believed that then-candidate Trump was "going to be okay on trade" and lauded Trump's understanding of trade.