Based on the Preface, Introduction and Chapters 1-4 of Ian Haney López's Dog Whistle Politics: How Coded Racial Appeals Have Reinvented Racism and Wrecked the Middle Class: How are minorities blamed for problems in society? How and why do many whites see themselves as victims?

In the introduction to the book, Lopez presents its central thesis, that "politicians backed by concentrated wealth manipulate racial appeals to win elections and also to win support for regressive policies" that benefit the very wealthy. This is part of his overarching concern, that despite the victories of the civil rights movement and changes in attitudes, deeply-held racist beliefs still structure American society. In short, ordinary white people have been persuaded to vote against their economic interests by politicians who make veiled racist appeals (i.e."dog whistles") and cynically play on their prejudices. Lopez (and many historians) use the Reagan Administration to illustrate this phenomenon. In Chapter Three, he shows that Jimmy Carter, a liberal, had tacitly defended white attempts to resist de facto integration (in schools and neighborhoods in particular), but the Reagan campaign in 1980 took this strategy to new depths. Lopez shows that Reagan coupled his policy proposals with "aggressive race-baiting." A man Lopez describes as a "key operative" (Lee Atwater, who would become one of Reagan's campaign directors in the 1984 election) famously described this strategy:

By 1968, you can't say [racial slurs]...Backfires. So you say stuff like forced busing, states' rights, and all that stuff. You're getting abstract, you're talking about cutting taxes, and all these things you're talking about are totally economic things and a byproduct of them is, blacks get hurt worse than whites.

Reagan, Lopez shows, used racially-coded language to rally white support for regressive policies like massive tax cuts and deregulation. This set him apart from politicians like George Wallace and Richard Nixon, who had used very similar language, but actually advocated relatively moderate political agendas. Reagan used rhetoric about so-called "welfare queens" who lived extravagantly while exploiting welfare programs to argue that hard-working whites were actually victims. Their paychecks were going to support the lifestyles of supposedly lazy people that whites would invariably imagine as minorities. He described a "strapping young buck," a heavily racially coded phrase, buying a steak with food stamps while "you were waiting in line to buy hamburger." Reagan had risen to prominence in California by advocating for "law and order," evoking images of Black Panthers and other radicals.
Lopez cites polling data that show Americans overwhelmingly support social welfare policies when presented in the abstract, but reject them at the polls. This, he argues, demonstrates the efficacy of the "dog whistle" appeals made by conservative politicians who seek to wreck these policies. The power of these appeals is such that many politicians have even embedded them in the appeals for "color-blind" justice once advocated by Martin Luther King. In this telling, explained in the fourth chapter, "reverse racism" has victimized hard-working whites and favored people of color.
https://books.google.com/books?id=20QSDAAAQBAJ&printsec=frontcover&dq=lopez+dog+whistle+politics&hl=en&sa=X&ved=0ahUKEwiClLvV6tveAhXpc98KHdjyAQgQ6AEIKjAA

Haney Lopez speaks about how the Republican party uses what he calls a "dog whistle," or a coded message to a target audience (page 4) to appeal to the shrinking portion of the electorate made up of white people. The "dog whistle" contains a thinly veiled reference to race and uses fear to blame nonwhite people for issues such as welfare fraud and illegal immigration; denies allegations that the GOP is pandering to whites; and denies nonwhites' claims of racial discrimination. In other words, while blaming race for many of society's problems, this form of dog whistling involves Republicans denying that they are doing so. The coded messages teach their audience that minorities are the cause of many of society's ills and that whites are the victims.
The first two chapters of this book trace the rise of the GOP as what the author calls "the white man's party" with Nixon and the turn to the party's use of what the author calls "strategic racism" to win votes. Chapter 3 discusses Reagan's use of "dog whistle" politics to dismantle the government's commitment to social welfare and the middle class, and Chapter 4 discusses the way in which "dog whistle" politics falsely promote colorblindness.