O'Rourke's comment came in response to Cruz's criticism of the Democrat's desire for a tax on oil production. "O'Rourke would blow it all!" he said.
Ted Cruz, the one-time presidential candidate whose Senate seat O'Rourke is aiming to capture next month. "It's why the president called him "Lyin" Ted, ' and it's why the nickname stuck ― because it's true". "Impeachment, much like an indictment, shows that there is enough there for the case to proceed", O'Rourke has said, "and at this point there is certainly enough there for the case to proceed".
Cruz, one of Trump's fiercest primary opponents that year, has since cultivated a close relationship with the president, despite Trump suggesting that his father was in on the plot to assassinate John F. Kennedy in Dallas and disparaging his wife's physical appearance on the campaign trail.
Texas is seen as one of the Democrats' best chances at picking up one of the two U.S. Senate seats, get a majority in the Senate and allow it to block Trump's agenda and exercise oversight of his administration. But polls that once showed O'Rourke within striking distance of a monumental upset now suggest Cruz may be edging further ahead.
But O'Rourke will need a comeback in conservative Texas, which has not elected a Democrat to statewide office since 1994.
"Well it's clear Congressman O'Rourke's pollsters told him to come out on the attack", Cruz said.
O'Rourke is trailing behind Cruz in the latest polls, despite his record-setting $38 million in campaign funds last quarter.
On healthcare, O'Rourke said he favors expanding Medicaid and getting to universal health care.
O'Rourke countered that Cruz was ineffective and self-serving in the Senate, more interested in his political career than in helping Texans.
The two also sparred over the issue of judicial appointments, and Cruz said he was "proud" to help confirm both of Trump's nominees to the Supreme Court - Neil Gorsuch and Brett Kavanaugh.
O'Rourke criticized Trump for alienating trade partners like Canada and Mexico, and said his trade war is "hurting no state more than it's hurting Texas".
"Really interesting to hear you talk about a partisan circus after your six years in the U.S. Senate", O'Rourke shot back, drawing laughs from the audience.
O'Rourke said there needed to be a greater focus on screening methods for people entering the country, and hit Cruz for his vote against a permanent solution for Dreamers, recipients of the Deferred Action for Childhood Arrivals program.
Cue a clip of Cruz declaring that "I'm a big fan of eating White Castle burgers".