Art Laffer is a famous economist, one of the brains behind President Ronald Reagan's supply-side tax cuts in 1981. But he was also a political adviser to Reagan and other presidential candidates. Based on history rather than polls or demographics, he insists Donald Trump will win the presidential race—and win easily.

History is an argument not often heard in presidential elections except in one case: the likelihood that after one party holds the White House for eight years, that party probably won't win four more years. The one exception in the past half-century was the election of George H.W. Bush in 1988 after eight years of the Reagan presidency.

But Laffer doesn't rely heavily on that case. Instead, he cites six historical parallels, comparisons, or developments that he says point inescapably to a Trump victory over Hillary Clinton in November.

The first is what Laffer calls "1979-1980: How the Reagan Revolution Began." Reagan "was disrespected and abused by significant segment of the Republican establishment," Laffer notes. "The torrent of anti-Reagan epithets never stopped."

Laffer's conclusion: "In other words, just like today in re Donald Trump, the party's cognoscenti were forecasting a huge Reagan defeat that would carry with it large numbers of House members and senators." But Reagan won in a landslide. "That Reagan saga of 1980 seems a lot like the Trump story today."

The second is the economy. "For Hillary Clinton, the Obama record on the economy will be her biggest negative come November," according to Laffer. "And the very fact that she actually sought out and embraces this legacy speaks volumes about her judgment."

It's a "challenge for the incumbent party to maintain the White House…even when a president's term ends on a high note," Laffer says. But when it ends with a weak economy, it's almost impossible. And the economy in the eighth year of the Obama presidency is indeed weak.

"This Obama economy really isn't a recovery, let alone a strong recovery, as one would expect should have happened following the devastating collapse of the Great Recession," Laffer says. "Why would Hillary Clinton want to run on the Obama record? It's beyond me."

Number three: the mood of the country. There's "a downside to being a Democratic insider and establishment figure today," Laffer says. "When the electorate is unhappy with the direction the country is heading," Hillary Clinton "will be blamed right along with the president."

Laffer uses the Gallup poll question, "Are you satisfied with the way things are going?" He says "its predictive power sincere is pretty impressive." When dissatisfaction is very high, the incumbent party's candidate loses, though that rule didn't apply in the 2012 election. But if it "reestablishes its predictive power in 2016, Trump wins in a Reagan-like landslide."

Number four is the vote in primaries as "a harbinger of general elections." The surge in Republican voting is "astounding" and speaks "volumes for Republican prospects in 2016…It's the Trump phenomenon plus much more…Republican turnout [in 2016] is way up, and Democratic turnout in way down. Someone should ring the Democratic alarm bell."

Laffer himself rings it. He notes that as of May 3, when Trump locked up the GOP nomination, 11 states "had Republican turnout in excess of Democratic turnout" after trailing earlier primaries. "When it comes to the electoral college, flipping a state" is enormously important, he says.

In Laffer's words, this is the fifth: "Politics bubbles up from the bottom and presidential selection is the final coup de grace of a political revolution." Republican majorities in "the U.S. House, U.S. Senate, state houses, state senates, and governorships, he believes, are accurate forecasters of presidential races." If this holds true in 2016, "Hillary Clinton is toast."

The sixth factor is the candidates' histories. Trump benefits from his career outside politics. This means he's "had very limited exposure as a practicing politician and, therefore, has only his own words and phrases to criticize," Laffer says. "But with Hillary, it's different. Hillary has done a lot." There's "a laundry list of her significant misdeeds." Yes, there is.