State Rep. Paul Sadler defeated retired teacher Grady Yarbrough in the Democratic runoff on Tuesday. With 10 percent of precincts reporting, the AP called the race with Sadler leading Yarbrough 63 percent to 37 percent.
Cruz is expected to easily win in November, given the GOP's significant advantage in the state.
Throughout the campaign, Cruz has said he will align himself with DeMint and other conservatives in the Senate, including Sens. Rand Paul, Mike Lee and Pat Toomey -- all of whom endorsed Cruz's candidacy.
Cruz's victory cements his status as a rising star in the Republican Party. During the campaign, Cruz appeared on the cover of the National Review and was profiled by conservative columnist George Will. The son of Cuban immigrants, he has drawn comparisons to Florida Sen. Marco Rubio.