AUSTIN, Texas -- County election offices throughout Texas are scrambling to process a massive backlog of voter registration applications stemming from an error at the state level, a headache that is hitting just as they are preparing for voting to begin in the midterm elections.

The problem, which officials in the Republican-controlled state have not publicly defined, also could have disenfranchised people who wanted to vote in the state's March primary but whose registration applications were never processed, local election officials said during a news conference Wednesday.

"This is really out of left field. Knowing that this one element of (state) applications didn't come through, and we had no insight on it," said Chris McGinn, executive director of the Texas Association of County Election Officials.