Updated March 3 at 3:34 p.m.: Revised to include Friday's early voting numbers.

AUSTIN — Early voting turnout for this year’s Democratic primary doubled since the last midterm election in 2014.

According to the Texas secretary of state’s website — which tracks only the 15 counties with the most registered voters — 205,583 people voted early in the 2014 Democratic primary. This year, 406,302 Democrats people voted early — a 98 percent increase.

On the GOP side, 352,963 people voted early in the Republican primary. That’s a 16 percent increase from 303,858 in 2014.

Democrats hold a 53,339 vote lead, but that doesn't mean all of the voters are Democrats. Since Texas has semi-open primaries, voters can choose which party's primary to vote in. (There is a caveat to choosing: In a runoff, voters must stick with the same party.)

Political experts attribute much of Texas' increased voter turnout as a reaction to the election of President Donald Trump in 2016, as well as the state's eight open congressional seats.

Harold Clarke, a political science professor at the University of Texas at Dallas, said one reason Democratic primary voting numbers are up is because people think Democrats have a reasonable chance of winning.

"One of the things we know is that competition stirs turnout, and it looks now that here in Texas, perhaps especially for the first time in a long time, winning the Democratic primary is really a prize worth having because you have a real shot at the general election," Clarke said. "That perception is fairly widespread both among potential candidates as well as Democratic voters."

Dallas County's traditionally strong Democratic base appeared to respond to that competition, with turnout increasing 93 percent from 2014. Republican turnout decreased 4 percent.

The jump in Collin County, which votes for more conservative candidates, is even greater -- the number of Democratic primary voters increased 248 percent from 2014, while Republican voters increased by 47 percent.

Chris Wilson, who does polling and research for Gov. Greg Abbott and Sen. Ted Cruz, said though the surge in Democratic turnout speaks more toward a lack of enthusiasm for their candidates in 2014.

“When it comes down to it, the Texas congressional and state delegation in November will look almost like it does today,” he said.

Wilson added that the increased enthusiasm from Democrats should demonstrate to Republicans that running bad campaigns won’t cut it anymore.

“These numbers should be a wake-up call to every single Republican running in Texas,” Wilson said. “If you do not run a campaign that speaks to voters at an individual level, you could lose. In past years in Texas, you could run a bad campaign and still win.”

According to Ryan Data & Research, 85 percent of early voters this year have a history of voting in Republican primaries, but not Democratic. Derek Ryan, who runs the research group that supports Republican campaigns, analyzed voter data from the top 17 counties with the most Republican turnout in the last primary election.

He said the biggest takeaway was that nearly a quarter of the people who voted Democrat this year had never voted in a primary.

“I don’t necessarily know who these people are, but my thinking is on the Democratic side, these are probably people who voted for Hillary Clinton or even straight party Democrat in the 2016 general election and prior general elections,” he said. “But this is the first time they’re getting involved in the Democratic primary process.”

Ed Sills, communications director for the state labor organization Texas AFL-CIO, said Republicans and Democrats often cross over to vote in the other party's primary.

"If you have people who are Democrats voting in a Republican race, they may tend to be trying to help people who are more moderate," Sills said. "And going in the other direction, Republicans voting in Democratic primaries, they may be trying to vote for someone more centrist."

He said the outcome could potentially decide close elections.

"Even those relatively small percentages makes a difference in someone getting into a runoff or winning outright," Sills said.

Ryan said if Republicans crossing over in the primary also vote for Democrats in the general election, it could change outcomes in down-ballot races but not at the top of the ticket.

“I don’t think it’s necessarily going to be a factor in statewide elections,” he said. “Now, having said that, 3 to 4 percent or whatever who has truly switched parties -- come November, that could sway some legislative races, maybe some congressional races or some down ballot in counties and districts across the state.”

Ryan also noted that 19 percent of the early votes cast in the Republican primary are mail-in ballots, while they make up 14.5 percent of the Democratic primary voting totals.

“I can't speak for Democrat campaigns, but I do know of multiple Republican candidates who have actively tried to get voters to vote by mail,” he said in his email. “This could be why these voters are a larger share on the Republican side.”