Jeremy Wallace, Houston Chronicle

Texans have already set a record for early voting in a non-presidential primary election year, and there’s still one more day to go on Friday.

More than 602,000 voters had cast ballots in the state’s largest counties in either the Democratic or Republican primaries through Wednesday. That does not count Thursday’s totals that were not available late Thursday, or Friday’s, when polls will again be open from 7 a.m. to 7 p.m. Four years ago, fewer than 600,000 people voted in the entire early voting season.

Harris County has also seen a new record. More than 116,000 people have voted early or by mail already with two days remaining to add to that total. Four years ago, just 105,508 people in Harris voted during the entire early voting period.

Democrats represent a major reason for the records and have been out-voting Republicans since the start of early voting on Feb. 20. There have been 25,000 more Democratic ballots than Republicans have cast. That is a big change from the last two gubernatorial election cycles when Republicans dramatically outvoted Democrats in the primaries by well over 100,000 in each year.

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Those numbers are partly driven by people who are new to primaries, said Austin-based political analyst Derek Ryan. In looking at voter data from about 50 counties, Ryan said he’s seeing that almost 20 percent of the Democrats voting in that primary have never voted in a Democratic Primary in Texas before. For Republicans that has been closer to 8.5 percent.

“This seems in keeping with what we have seen over the last year,” said Cliff Walker with the Texas Democratic Party.

Democrats have been boosted this year by a combination of factors this year. Opposition to President Donald Trump has been a big factor in turning out voters nationwide, but Democrats also have been aided by more candidates running for office and more competitive primaries than four years ago. Four years ago, in the nine congressional districts that make up parts of Harris County, just two had competitive primaries for Democrats. This year, seven of the nine have Democratic primaries.

In Harris County, 59,048 people had voted in the Democratic Primary compared to 57,108 in the Republican Primary.

While the primary numbers are up overall, Rice University political science professor Mark P. Jones said it has to be put in context of Texans being terrible at turning out to vote overall. In the last gubernatorial election cycle, Texas was dead last in voter turnout compared to other states.

The primaries are just as bad if not worse, he said. Despite having nearly 28 million people, just 1.5 million to 2 million people will vote in the primaries, Jones said. As a result, because of the nature of the state’s politics and gerrymandering, many races are decided almost entirely in the primary, with relatively few voters having a say in it.

“Not only do we have the lowest turnout in the nation, our primaries are far more consequential than in other states,” Jones said.

Texas has even done pretty well in making it easier to vote in primaries, he said. In other states, voters have to register with a party 30 days or more before and election to be able to vote. And many other states don’t have early voting with as many locations as Texas. Yet, still, he said Texans just don’t turnout like in other states.

While early voting ends Friday, the official Election Day is Tuesday, in what is the nation’s first primary election in 2018. There is a lot at stake. Texas voters will decide who will carry the Democratic party’s mantle into the battle for governor and a slew of other statewide offices in the nation’s biggest GOP stronghold, remake the state’s congressional delegation with many new members likely determined during the primary in heavily gerrymandered districts, and test Sen. Ted Cruz in his first re-election since his stunning victory in 2012.