With a chance to play a decisive role in the Democratic presidential primary, Texans in the state’s largest counties swarmed to the polls for early voting in numbers that eclipsed a sky-high showing in 2016 for the party.

Yet with President Donald Trump all but certain to win the GOP primary at the top of the ballot, voters in the state still cast even more early votes in the Republican primary than the Democratic contest, 1,070,278 to 954,583.

That nearly 7 percent turnout on the Democratic side for the 15 counties with the most registered voters was above the 5 percent racked up after early voting in the 2016 presidential primary.

On the Republican side, the nearly 5 percent turnout in those counties didn’t quite peak to the 7 percent that it was in 2016.

The blockbuster turnout is yet another sign of the growing competitiveness of Texas elections and its emerging role as a battleground state, said Brandon Rottinghaus, a political science professor at the University of Houston.

“If there’s one thing we know in political science, it’s that competitive elections drive turnout through the roof, and Texas has had more frequent competitive elections in the last couple of cycles than it’s seen for the past decade,” Rottinghaus said.

And it’s not just a crowded Democratic presidential primary that’s spurring the outpouring. That boost in turnout among both parties signals that downballot races — including the 22nd Congressional District race in Fort Bend County for retiring Rep. Pete Olson’s seat and 7th Congressional District race for the seat Rep. Lizzie Fletcher flipped in 2018 — are also motivating voters to show up at the polls, Rottinghaus said.

In Harris County, about 5.8 percent of registered voters, or 139,533, had cast a ballot in the Democratic primary by the end of early voting, compared with 4.4 percent, or 104,909, in the Republican primary. That’s up from the 4 percent that it was in 2016 for Democrats but missed the mark from the more than 6 percent for Republicans that year.

Meanwhile, in Bexar County, the Democratic primary also was outpacing the Republican contest with 6.9 percent, or 78,206 Democratic votes, over Republicans’ 3.8 percent turnout, or 43,970 votes by the end of early voting from in-person ballots alone. Those numbers put the county above Democrats’ 5.6 percent showing in 2016 but well below the Republicans’ 6.2 percent that year.

Know the candidates: San Antonio Express-News 2020 primary election voter guide; Houston Chronicle 2020 primary election voter guide

Experts cautioned that early voting data should be taken with a grain of salt — for one because the subset of people who vote early aren’t necessarily representative of the entire state.

Texans who vote early tend to be older, economically well-off and better educated and tend to live in urban and suburban areas as opposed to rural ones, according to a 2010 study by Austin Community College.

A lot could change by Super Tuesday, March 3 — in particular how South Carolina’s primary on Saturday might affect undecided Democratic voters in Texas. An untold number of voters have been holding out for those results before voting; others who may not have voted otherwise may be spurred into action by a shift in the race.

“Let’s put it this way: So much happens every day in politics, voters want to wait until the last minute to decide,” Rottinghaus said. “So we could see turnout bigger on election day because you’re going to see more things happen between the end of early voting and election day.”

The process of voting has also become more accessible for a wider swath of Texans after four of the top five largest counties in 2019, including Harris and Bexar, moved to allow countywide vote centers, meaning polling places are open to all voters no matter where they live. That switch could also boost turnout.

For subscribers: Early voting way up in Texas, compared with four years ago, for Democrats

Republican strategist Derek Ryan said the high numbers of voters casting Republican ballots early surprised him, especially with a noncompetitive presidential primary.

“There isn’t really anything necessarily motivating people at the top of the ticket,” Ryan said. “But turnout right now on the Republican side is above what it was in 2008 and 2012. It’s actually closer to what turnout was at this point in 2016 with a contested presidential primary.”

Ryan said he attributes that to the strength of Trump’s base who are “trying to send a message that they’re behind him” as well as the number of competitive congressional races across the state.

While Democrats’ numbers are high, Ryan said he expected to see the presidential race propel even greater turnout, and he noted that they nowhere near the explosive turnout of 2008 when Barack Obama and Hillary Clinton were going head-to-head for the presidential nomination. That year, turnout in the primary was at about 23 percent for Democrats, with 2.8 million casting ballots, compared with about 11 percent for Republicans, or 1.3 million votes.

Rottinghaus, however, said that year may not be the best comparison point, considering that an unknown number of Republicans were said to have voted in open primaries as part of “Operation Chaos” to hurt Obama’s chances. Obama and Clinton were also much different candidates, both very well-known and with strong establishment support, compared with the assortment of candidates available to 2020 voters, he said. Texas also at the time still operated under a two-step process that included a caucus and a primary.

Texas Democratic Party spokesman Abhi Rahman said he’s “over the moon” about the way that early voting has gone so far, especially that Democrats are outpacing turnout from 2016 by about 200,000.

“We’ve significantly closed the gap,” Rahman said about Democrats’ share of the vote. “We always knew they would outvote us in early vote, but there is essentially no gap this time.”

Democrats were similarly encouraged in 2018 when they saw big early voting gains; yet, when Election Day returns were tallied, the highly anticipated “blue wave” still fell short of turnout on the Republican side. But Rahman said he expects the momentum from early voting to stick this year.

“The energy we see is up and down the ballot,” Rahman said. “It’s not just the presidential. Texans want to flip Texas blue.”

Republicans also seem to be highly energized, Republican Party of Texas spokesman Sam Pohl said. Voters are encouraged by the healthy state of the economy and want to show their support for the Republican leadership that made that possible, Pohl said.

“We’re seeing a lot of excitement in the primary,” he said. “We’re seeing good turnout, and we’re pushing hard to increase that even more, and of course, Republicans turn out in even greater numbers on Election Day.”