Donald Trump Jr. campaigned for U.S Sen. Ted Cruz, R-Texas, Wednesday, proclaiming his father's onetime bitter rival a vital ally in Washington.

WICHITA FALLS — Donald Trump Jr. campaigned for U.S Sen. Ted Cruz, R-Texas, Wednesday, proclaiming his father's onetime bitter rival a vital ally in Washington and warning the GOP faithful not to be lulled into complacency amid fervent "hate" on the left for the president.

"If there's one thing Donald Trump lied to you about — don't worry, it's not a gaffe — it's that you'd be sick of winning," Trump said to a rally of more than 1,000 people at the Multi-Purpose Event Center. "Are you guys sick of winning yet?"

"No," the crowd replied.

"Are you sure?" he asked.

"Yes," they replied.

Photos: Sen. Ted Cruz holds rally with Donald Trump Jr. in Wichita Falls "We are getting everything we wanted, checklist after checklist, so we are getting a little fat and lazy. The other side is motivated by nothing but hate," Trump said, adding the economy's metrics are all so good that President Barack Obama is trying to take credit.

But, Trump said, "Hate is a powerful motivator. That's why we need a stalwart like Ted."

And, Trump said, "We are not participation medal kind of people, are we? We are going to run up the score, because it's about time."

Sanders soulmate?

Cruz is locked in a tougher-than-expected re-election race against U.S. Rep. Beto O'Rourke, D-El Paso, and Trump's appearances Wednesday with Cruz in Wichita Falls and Conroe are part of a national effort to stoke Republican turnout by turning the midterm election into a referendum on President Donald Trump.

“That’s why we’ve got to ring the bell for Ted Cruz,” Trump Jr. told KTSA radio host Trey Ware on Tuesday. “All the MAGA (Make America Great Again) people have got to realize, Trump is on the ticket in November.”

President Trump made the same point at his rally Tuesday in Mississippi.

"I’m not in the ticket. But I am on the ticket because this is also a referendum about me,” President Trump said. "I want you to vote. Pretend I’m on the ballot. And don’t worry, we’ll be on the ballot in two years, and we will do a landslide again."

The Cruz campaign is seeking portray O'Rourke and Vermont's U.S. Sen. Bernie Sanders as ideological soulmates in an effort to polarize the electorate.

State Rep. Drew Springer, R-Muenster, warming up the crowd, said he admired Sanders, and asked if the crowd didn't also, drawing boos as he explained that Sanders is honest about being a socialist, while O'Rourke pretends he isn't.

Cruz attacked O'Rourke as an enemy of law enforcement, of strong borders, of gun rights and of Israel, and a supporter of "full-on socialized health care."

Talking about his support for universal health care Tuesday at Austin Community College, O'Rourke had said he and others risked being branded as socialist for their advocacy, but he asked the audience to imagine if Franklin D. Roosevelt or Lyndon B. Johnson had been cowed by similar denunciations when they implemented Social Security, Medicare and Medicaid, which are now bipartisan sacred cows.

'Incredible victories'

Cruz and the elder Trump were bitter antagonists at the close of the 2016 GOP primary contest, and Cruz was slow to endorse Trump after he became the party's nominee.

But the president's son said that Cruz, rising above the acrimony, came around — "a testament to this man's character."

With Trump as president, Cruz said, "We are winning incredible victories for the American people."

And, noting that Trump Jr. "endures attacks and grief and nastiness," and the president "endures even more attacks and grief and nastiness," Cruz said, "Thank you for fighting for this country and ignoring the hatred on the other side."

Trump Jr. was accompanied by his girlfriend Kimberly Guilfoyle, a former Fox News host and former first lady of San Francisco and ex-wife of California Democratic gubernatorial candidate Gavin Newsom. She is now vice chairwoman for the pro-Trump super PAC, America First Action. She offered brief words of praise for Cruz.

As he took the stage, Trump Jr., who described himself as "basically a Fifth Avenue redneck," surveyed the large crowd and said, "Not bad for 4 o'clock in the afternoon. I like it."

"There are 10 press and 10 protesters, so basically 20 protesters," he added.

The first arrival at the event, more than three hours before it began, was Doug Milyiori, who manages a Bed, Bath & Beyond store in Wichita Falls. He brought his three sons — Dominic, 17, Nicolas, 14, and Gabriel, 13 — whom he took out of school for the occasion.

“It's a very important election,” Milyiori said. “I don't want to talk bad about people, but the left has just gone crazy, violencewise, yelling at people all the time.”

As an example, he cited the folks who recently chased Cruz and his wife, Heidi, out of a Washington restaurant, upset with the senator’s support for Brett Kavanaugh’s nomination for the Supreme Court.

“Man, that’s family time, just leave the guy alone,” Milyiori said. “You don’t see Republican protesters doing that to Democrats.”