WASHINGTON — Voter turnout soared in the 2018 midterm elections, according to an early projection in a new study, potentially reaching the highest level in over 50 years.

An estimated 48.1 percent of eligible voters cast ballots, over 113 million people in total, according to research by University of Florida Professor Michael McDonald, who runs the U.S. Election Project. If that holds it would be the highest rate since 1966, when 48.7 percent of voters participated.

The numbers are still subject to change as states continue to report final vote counts, especially places like California, where voters can mail in their choices all the way up to Election Day and large numbers of ballots have yet to be counted.

The high turnout, which was presaged by a surge in early votes, as well as primary and special election votes, comes after voters participated at historically low rates just four years ago in the 2014 midterms. Just 36.7 percent of voters cast ballots that year, the lowest percentage since World War II.

McDonald attributed the increase to a variety of factors, including more high-profile and competitive Senate and governor races in key states. The House, which flipped to Democrats, was also much more hotly contested this year in comparison to 2014, when Republicans were considered prohibitive favorites to maintain control.

Texas, which had the lowest turnout in 2014 amid mostly non-competitive state races, saw its turnout rate spike as voters went to polls in the closely watched Senate race between Republican Sen. Ted Cruz and Democratic challenger Beto O’Rourke. But the effect also extended to states like North Carolina, which saw high turnout despite an off-year for both senate and gubernatorial elections.

But the biggest factor seems to be President Donald Trump. Unlike previous midterms, where one party's voters showed up in high numbers and the other remained depressed, the high turnout rates suggest voters across the board were eager to participate. Exit polls found two-thirds of voters identified Trump as important to their vote, either to show their support or register their opposition.

"Let's give Trump some credit: He inflames passions for both Democrats and Republicans," McDonald said.