Republican presidential candidate Texas Sen. Ted Cruz speaking in Atlanta. (Scott Olson/Getty Images)

ATLANTA — Ted Cruz, facing stagnant poll numbers just days away from the crucial Super Tuesday contests that span the country, tore into Republican front-runner Donald Trump here Saturday afternoon, calling the mogul an untrustworthy insider who is far too cozy with liberal Democrats.

“If we nominate Donald, we end up electing Hillary as president,” Cruz warned Republicans at a Liberty Plaza rally, casting Trump as unfit and unready for a general election campaign against Democrat Hillary Clinton. “I don’t think it makes sense to nominate a candidate who has agreed with Hillary on issue after issue.”

Turning to another rival, Marco Rubio, who has picked up traction after early stumbles, Cruz criticized the Florida senator's latest “battle of insults” Trump as unnecessarily personal and petty.

“I don’t think it’s a good thing to see presidential candidates just behaving like schoolchildren bickering,” Cruz said at a news conference prior to the event. He described his own critiques of Trump as based on “substance” and “policy.”

The Texas senator’s 20-minute remarks, under a hot sun in a plaza outside the gold-domed state capitol, were his latest attempt to underscore his core argument to GOP voters ahead of the 11 contests on March 1: He’s an authentic conservative outsider with an ideology forged by years of legal and political battles.

“If you want someone who will go and cut deals with Barack Obama and Harry Reid and Nancy Pelosi, you’ve got candidates who have done so and who have promised to do so,” Cruz said. “But if you want someone who stands up to Washington, ask yourself who has stood up to Washington.”

But Cruz continues to find it difficult to counter the relentless media appearances and headline-making barbs of Trump, who has ridden his populist and combative pitch to the top of national polls and three straight victories in the Republican primary race — and growing support from right-wing luminaries.

Republican presidential candidate Ted Cruz said "we have six days to stand together" on Super Tuesday in a reference to the Alamo, during an event in Houston, Tex., on Feb. 24. (Reuters)

There were signs here that Cruz still has work to do to close the gap between him and Trump as both try to stitch together conservative coalitions. Several cars parked near the site had Trump bumper stickers along with Cruz stickers, as if their owners liked both candidates but can’t seem to pick a favorite.

The sprawling plaza was about 75-percent full, with hundreds of Cruz supporters bunched up near the concrete stage but ample patches of freshly cut grass were empty.

As people strolled in and picked up campaign buttons from wicker baskets, former Georgia congressman Robert L. Barr Jr., a libertarian-leaning Republican and Cruz ally, took hold of the microphone and spoke disdainfully of the billionaire.

“Unlike Donald Trump’s friends, [those in the crowd] are real Americans,” Barr said, running through a list of prominent Democrats who have received donations from Trump in the past.

Minutes later, a jeans-clad Cruz slowly paced before supporters waving signs and Gadsden flags. His delivery was contained and self-assured. He mixed his usual critical lines about President Obama with urgent talk of the impending primary showdown.

Cruz called March 1, where 595 delegates are up for grabs, the “most important day in this entire cycle” and reminded those standing before him about his win last month in the Iowa caucuses. “Only one candidate has beaten and can beat Donald Trump,” he said.

Cruz kept the rest of his speech tight, sticking to the themes of a stump speech that has carried him for months. There was a pledge to “rip apart” the Iranian nuclear deal, assurance that he would appoint a conservative to the Supreme Court and a promise to end the Obama administration’s executive orders.

And Cruz, who has been a hero to many movement activists ever since he was elected, insisted that the grass-roots energy that lifted him in congressional fights in recent years remains palpable, in spite of the rise of Trump and the race’s strange turns.

“People are waking up,” Cruz said, gesturing at attendees. “There is a spirit of awakening that is sweeping this nation.”

But come Tuesday, he said, they better turn out.

“Vote for me 10 times,” Cruz joked, quickly adding that he was not suggesting voter fraud.

“We’re not Democrats,” he said.