AUSTIN — Early voting for the March primary is more than half over, and Democrats have outpaced Republicans at the polls on each day.

Through Sunday in the 15 Texas counties with the most registered voters, 135,070 people had voted in the Republican primary and 151,236 in the Democratic. Compared with the first six days of early voting in 2014, Democratic turnout increased 69 percent, while Republicans saw a 20 percent increase.

The Democrats even surpassed their early voting totals from the 2016 primary — a presidential election year.

Sen. Ted Cruz told a group of Republican voters this month that the left would "crawl over broken glass in November to vote. ... We could get obliterated at the polls," and other Republicans appear to be taking the Democratic surge seriously. Gov. Greg Abbott's campaign sent supporters an email Monday asking for donations to help him get out the vote, warning that the early voting numbers "should shock every conservative to their core."

“I’ll be blunt: Democrat voter turnout is surging statewide during Early Voting,” reads the email, using bold and italicized red print. The email states that the last time Democratic primary voters came out so strongly was in the 1990s, during a gubernatorial election cycle, and that Democrats are flipping seats in special elections across the country in Republican strongholds.

“We’ve seen a surge of liberal enthusiasm in deep red states like Georgia, Alabama, and Oklahoma,” the email says. “We had always hoped the liberal wave would never hit Texas, but these early voting returns aren’t encouraging so far.”

Well, that was almost predictable. Okay it was totally predictable #TxLege pic.twitter.com/KP0xxstKK8 — Scott Braddock (@scottbraddock) February 26, 2018

Brandon Rottinghaus, a political science professor at the University of Houston, said it’s interesting that Democrats are turning out at a rate more frequently seen in presidential election years. After looking at the relationship between primary and general election voters, he concluded that more votes in Democratic primaries correlate with more Democratic votes in general elections. But he said Republicans usually turn out in higher numbers to vote in the general election no matter how they voted in the primary.

“Usually Republicans tend to run up the numbers in the general and are beating their opponents by big margins, so the relationship is not positive, but it is for Democrats,” Rottinghaus said. “Because the [Democrats’] enthusiasm is so high, you’re likely to see more support for Democrats in November and that’s likely to cut into the margins that they’ll lose to Republicans.

“They’re still going to lose, but they’re going to lose by smaller numbers. In red Texas, that is a win.”

Tariq Thowfeek, Texas Democratic Party communications director, said the increase in voter turnout since the last midterm election shows that Texas Democrats are “marching, organizing and most importantly, they are voting.”

"Texans are fed up with Trump Republicans targeting our families, destroying our economic futures, and sabotaging our health care,” Thowfeek said in a written statement. “This year, we have a historical amount of candidates running in the Democratic primary. All of them believe this great state of Texas is worth fighting for."

James Dickey, chairman of the Republican Party of Texas, urged Republicans to go to the polls during early voting.

“We look forward to seeing the results of the primary election on March 6th, and to keeping Texas red in 2018,” he said in a prepared statement.

Harold Clarke, a political science professor at the University of Texas at Dallas, said that midterm elections are viewed as referendums on national politics, but that there’s no way to predict how what’s happening in Washington will affect races in the U.S. or in Texas.

“With the presence of Trump and the incredibly bitter politics in Washington, we just don’t know how that’s going to play out, but it could be influential in races across the country,” he said. “A strong dose of caution is in order right now.”

Early voting runs through Friday.