The Rio Grande Valley district in Southern Texas will be represented by Republican Mayra Flores following her victory in a special primary election.
Flores will be finishing the term of former Democratic Rep. Filemon Vela who resigned at the end of March.
Flores, a GOP organizer and the daughter of migrant workers, will only hold the seat for a few months until the district is redrawn and the next primary election is held in November.
While it is expected that the new district will favor Democrats, Flores' victory in the largely Hispanic Rio Grande Valley is a threatening sign for Democrats.
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The special primary loss shows Democrats are losing ground in an area they once controlled. Flores' success also highlights how Republicans are making inroads with Hispanic voters.
Flores' win has implications for Democrats nationally. The loss denies House Speaker Nancy Pelosi the opportunity to increase her two-vote margin in passing legislation.
NBC News reported Flores will hold the seat until January under the district's old lines.
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In November, there will be a general election to decide who represents the new 34th District, which favors Democrats much more than the current district, NBC News reported. The nominees for that race have already been decided in the normal primary process: Flores will face off against Democratic Rep. Vicente Gonzalez under the new lines.