Krugman wrote that these policies were unsustainable in the long run and would eventually generate a major economic crisis. The book was a best-seller. In 2007, Krugman published The Conscience of a Liberal, whose title refers to Barry Goldwater's Conscience of a Conservative. It details the history of wealth and income gaps in the United States in the 20th century. The book describes how the gap between rich and poor declined greatly during the middle of the century, and then widened in the last two decades to levels higher even than in the 1920s. In Conscience, Krugman argues that government policies played a much greater role than commonly thought both in reducing inequality in the 1930s through 1970s and in increasing it in the 1980s through the present, and criticizes the Bush administration for implementing policies that Krugman believes widened the gap between the rich and poor. Krugman also argued that Republicans owed their electoral successes to their ability to exploit the race issue to win political dominance of the South. Krugman argues that Ronald Reagan had used the "Southern Strategy" to signal sympathy for racism without saying anything overtly racist, citing as an example Reagan's coining of the term "welfare queen". In his book, Krugman proposed a "new New Deal", which included placing more emphasis on social and medical programs and less on national defense. In his review of Conscience of a Liberal, the liberal journalist and author Michael Tomasky credited Krugman with a commitment "to accurate history even when some fudging might be in order for the sake of political expediency". In a review for The New York Times, Pulitzer prize-winning historian David M. Kennedy stated: "Krugman’s chapter on the imperative need for health care reform is the best in this book, a rueful reminder of the kind of skilled and accessible economic analysis of which he is capable". In late 2008, Krugman published a substantial updating of an earlier work, entitled The Return of Depression Economics and the Crisis of 2008. In the book, he discusses the failure of the United States regulatory system to keep pace with a financial system increasingly out-of-control, and the causes of and possible ways to contain the greatest financial crisis since the 1930s. In 2012, Krugman published End This Depression Now!, a book which argues that looking at the available historical economic data, fiscal cuts and austerity measures only deprive the