O'Rourke, a three-term congressman who had the backing of the national party, won about 62 percent of the Democratic primary vote Tuesday night, fending off a challenge from Sema Hernandez, who won nearly 24 percent, and Edward Kimbrough with 14.4 percent.
Hernandez, a 32-year-old member of the Democratic Socialists of America, surprised some political observers by beating O'Rourke handily in dozens of counties, including almost every one along the U.S.-Mexico border.
FIRST LISTEN: our new 60-second statewide radio ad introducing our liberal opponent, Congressman Robert O’Rourke, to Texas voters.— Ted Cruz (@tedcruz) March 7, 2018
Help #KeepTexasRed: https://t.co/PVsiCtbbyL #CruzCrew #TXSen pic.twitter.com/OxK61gZ0ek
Nonetheless, O'Rourke will now seek to become the first Democratic senator from Texas since former Sen. Robert Krueger in 1993.
But he'll face a stiff challenge from Cruz, who released an attack ad jingle immediately after O'Rourke's primary win was solidified that insinuates he is pandering to Hispanics by using the name "Beto" instead of his birth name, Robert.
"I remember reading stories, little Robert wanted to fit in. So he changed his name to Beto and hid it with a grin," the song's lyrics state. "Beto wants those open borders and wants to take our guns. Not a chance he'll get a vote from millions of Texans."
O'Rourke, who is white, has said before that his parents began calling him Beto when he was a child.
Cruz, meanwhile, is of Cuban descent and goes by the more English-sounding "Ted" instead of his birth name, Rafael.
But O'Rourke said he doesn't plan on getting involved in political mud-slinging.
"I'm not running against anyone. I'm running with the people of Texas to do something really great for this country," he said, according to the Dallas Morning News. "There's really not much I need to say about Sen. Cruz. I trust the people of Texas. I trust their ability to make their own judgments."
According to NBC DFW, Texas' primary turnout on Tuesday was the highest in the state since 2002 with more than 960,00 Democrats and 1.4 million Republicans going to the polls. But Democrats had a higher percentage increase.
When asked if he was worried about an anti-Trump backlash in Texas that could affect him in the general election against O'Rourke, Cruz said he wasn't.
"The extreme left is angry and energized and they hate the president," Cruz said in a call to reporters. "But the good news is there are more conservatives than there are liberals in Texas."