The 2018 election process in Texas takes place over several months with candidates campaigning through the fall, winter, and early spring. They take part in a party Primary before facing off with other parties candidates in the General Election.
Both the Republican and Democratic parties of Texas hold primaries in the March of even years. The 2018 Republican Primary will be held on March 6, 2018 with any possible runoff elections being help on May 22, 2018. Voters in Texas may vote in either primary, but are only allowed to vote in 1 party’s primary per election cycle. If a voter did not vote in the initial primary, they may vote for either party in the event of a run-off election. A voter may not vote in another parties run-off election if they voted in another parties primary.
Republican Primary voters elect the Republican candidates who will appear on the general election ballot, their precinct chairmen, and their county chairmen. Thus, primary voters have a greater influence on the final outcome of the general election than those who only vote in the general election.
Those who vote in the Republican primary election (either in person or by mail) can then attend the various Republican Party conventions held that year. -Republican Party of Texas