(Radio Iowa) — Iowa is again among the small group of battleground states that may decide this year’s presidential election. David Schultz is the author of “Presidential Swing States: Why Only Ten Matter” — and he puts Iowa is that group. “It has been a state where both Republicans and Democrats have been competitive and actually over the last 40 years, Republican presidential nominees and Democratic presidential nominees have actually won the state,” Schultz says.

Over the past 40 years. Republican candidates won four presidential elections — in 1980, ’84, 2004 and 2016 — and Democrats won the other six presidential races here — in 1988, ’92, ’96, 2000, 2008 and 2012. Schultz says Iowa has a classic mixture of characteristics that make it a swing state in presidential elections. “Iowa, like the other swing states, has a high percentage of voters who declare themselves to be independent.

Also Iowa, like many of the swing states, is really sort of two states — the eastern part of the state being more Democratic and the western being more Republican and also one more,” Schultz says. “It has both a high percentage of college educated people and still a high percentage of white working class.”

David Kochel, who managed Mitt Romney’s Iowa campaign in 2012, says Donald Trump’s nine-point margin of victory in Iowa four years ago was a bit of an outlier. “And it was all baed on a deep-seeded antipathy to Hillary Clinton,” Kochel says. “Other than, of course, Chuck Grassley’s races and a few of Governor Branstad’s, we’ve had competitive elections at almost every level.”

Romney’s running mate held an Election Eve rally at the Des Moines airport back in 2012. And, on the same night, President Obama rallied with thousands in downtown Des Moines. Brad Anderson was state director of President Obama’s 2012 Iowa campaign. “As Iowa becomes more and more of a battleground state, which all of the polls suggest that it is, it is smart on both campaigns parts to schedule a visit here in the closing days of the campaign,” Anderson says.

Vice President Pence will headline a rally at the Des Moines Airport Thursday afternoon and, on Friday, Democratic presidential nominee Joe Biden is scheduled to campaign in the state. Drake University political science professor Dennis Goldford says in-person appearances are a boost because ads have diminishing returns at this point in the campaign. “Face-to-face, even in a pandemic era, is a welcome change. That’s why the president does so much of it,” Goldford says. “But even for Vice President Biden to come to Iowa, he’s showing the flag.”

Twenty years ago, George W. Bush beat Al Gore in Iowa by fewer than five-thousand votes. In 2004, Bush won the state by 10-thousand. Both margins of victory were less than one percent. Recent polls have shown the 2020 presidential race in Iowa may be just as close.