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.
On Election Day, the polls will be open from 7 a.m. until 7 p.m.
He said the outcome could potentially decide close elections.
Already, more than 49,000 Tarrant County voters have cast ballots - 29,200 in the Republican primary and almost 20,000 in the Democratic primary, according to local election results through Wednesday. This year, 310,275 people voted in the Democratic primary in the same span - a 92 percent increase.More news: JR Smith suspended by Cavs for detrimental conduct
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Jose Tellez encourages everyone to cast their ballots.
At stake in this year's primary elections are a number of contested races ranging from fights for the U.S. Senate and House of Representatives to the battle for the Texas Legislature and local courthouses.
For the last two gubernatorial election cycles, Republicans surpassed Democrats in the primaries by over 100,000 votes each year, the Laredo Morning Times reported.
In the previous election, the overall number of early voters totaled 19,000. Let us know if you have voted yet or plan to. There are 134,133 registered voters in McLennan County.