Democrats have knocked Cruz and other Republicans for opposing a bipartisan bill negotiated with Republican Sen. James Lankford, R-Okla. Cruz says he voted against the bill because it would have normalized thousands entering the country illegally every day and would have handed billions to nongovernmental organizations helping the migrants.

What to know about Republican Sen. Ted Cruz and his Democratic challenger, U.S. Rep. Colin Allred, as the pair fights for Cruz's U.S. Senate seat.

Republicans have a stranglehold on every statewide elected office in Texas and control the state Supreme Court, both chambers of the Legislature and both U.S. Senate seats.