Supporters of President Donald Trump lined up 24 hours ahead of a scheduled rally in Texas at the Toyota Center.
Trump has also called O'Rourke, the darling of white left-wing Hollywood elites and their media allies who share his sensibilities, a "lightweight".
Out on the 2016 campaign trail, Trump and Cruz had a less-than-friendly relationship and constantly hurled insults at each other.
"Donald, you're a sniveling coward, and leave Heidi the hell alone", Cruz said in response.
Set to appear with the president at the rally is Sen.
Cruz's race against the El Paso congressman was the main attraction over the weekend, and the senator basked in two rowdy crowds Saturday, first in Houston and then in Beaumont, as he campaigned with Fox News host Sean Hannity and Rick Perry, the USA energy secretary and former Texas governor.
But now, any bad blood between the two Republicans is behind them. Cruz said he put his "personal hurt feelings" aside and sought to work with Trump. "It's only a question of time". Only in September 2016 did Cruz eventually say in a Facebook post that he was voting for Trump.
"No, I like Ted". It was a very competitive, it was a very tough campaign. We actually held a rally together late into the campaign. He's not. I think he got beaten badly in the debates. "It all worked out, very nicely". We've done great on regulation cuts.
"That was a real concern because he had just endorsed two weeks earlier", said former Trump campaign aide Andy Surabian.
"I am not aware of a lot..." "And he's a very smart guy", Trump said. His Democratic opponent, Texas Rep. Beto O'Rourke, has already said that he would.
"I don't know that it makes any sense to respond", O'Rourke told ABC News. What I heard about him, I figured he must be something a little special. "I think it's more like wave bye-bye to the blue".