Texas Sen Ted Cruz has been called out for attacking his Democratic opponent for using a nickname, even though he does the same thing.

Mr Cruz was giving an interview on CNN Tuesday night when Chris Cuomo brought up a campaign jingle that mocks Rep Beto O'Rourke for going by Beto instead of his given name, Robert. Mr O'Rourke won the Democratic primary that same night, and will be competing to unseat Mr Cruz this November.

"You go after Beto for his name. Beto is obviously a nickname — why?" Cuomo asked. "First of all, you didn't like that dirty pool when you were running for president and the President called you 'Lyin' Ted', you didn't like that kind of tactic."

"And you know what, your name is Rafael, you go by Ted but your middle name is Edward, that's a more Anglicized version of it," Cuomo continued. "He went the other way and has a more ethnic version of his name — why go after him? You're doing the same thing."

Mr Cruz then agreed — sort of.

"You're absolutely right, my name is Rafael Edward Cruz," he said. "In terms of the jingle, some of it is just have a sense of humour."

Mr O'Rourke has dismissed the jingle, which says that the candidate changed his name to "fit in" with Democrats.

"I just don't think that's what folks in Texas want us to focus on," Mr O'Rourke said in a separate CNN interview. "We can get into name calling or talk about why the other person's such an awful guy, or we can focus on the big things we want to do for the future of our country."

What appears to be a strong pro-Democratic sentiment in the United States in response to the presidency of Donald Trump has left some wondering if Mr Cruz might be in danger of losing his seat, even though Texas has historically been a reliably Republican stronghold.

Mr O'Rourke has given some hope to his backers, out-fundraising Mr Cruz last quarter and showing that he plans on aggressively campaigning in the coming months.

Still, his chances of winning at this point are still something of a long shot. The likely voter population in Texas leans Republican, according to Gallup polling last year, meaning that the Democrat would have to launch a strong get out the vote effort and inspire a lot of enthusiasm.

There is little polling on the race at this point, but the few surveys that have been conducted so far suggest that Mr Cruz is favoured, even though Texans disapprove of the leader of his party — Mr Trump — about as much as the country as a whole does.