Rafael Edward Cruz is making fun of his Democratic opponent for going by a nickname.

Haven’t heard of Rafael Cruz before? That’s because Rafael is better known as Texas Senator Ted Cruz, who goes by a nickname of his middle name. But this week, his campaign released a radio advertisement making fun of Democratic opponent Beto O’Rourke for going by the nickname Beto rather than his given name, Robert.

“Liberal Robert wanted to fit in, so he changed his name to Beto and hid it with a grin,” the song says.

When Ted Cruz appeared on CNN, he was grilled about the apparent double standard and Cruz said that his campaign was just making a joke.

“In terms of the jingle, some of it is just having a sense of humor,” Cruz said in an appearance on New Day. “We had some fun with it.”

When asked why he would make fun of his Democratic opponent for going by a nickname when he does the same thing, Ted Cruz said he was not ashamed of his own name.

“You’re absolutely right. My name is Rafael Edward Cruz,” Cruz acknowledged. “I am the son of my father Rafael Cruz, an immigrant from Cuba who came to Texas with nothing.”

Once considered a safe seat, Ted Cruz has suddenly found himself in a competitive race amid a wave of interest from Democratic voters. Cruz has called out O’Rourke in a conference call with reporters, the Washington Post noted, taking on the Democratic candidate’s stances on gun control, the Affordable Care Act, and his stances on immigration reform.

The last time that a Democrat was elected to a statewide office in Texas was 1994, the report noted, but this year is seen as increasingly competitive and O’Rourke has taken measures to build name recognition and boost fundraising efforts.

Beto O’Rourke could also ride the momentum of a national wave of interest among left-leaning voters. As the Washington Post pointed out, turnout in this week’s Democratic primary in Texas was especially high, signaling an especially high level of interest. Political pundits say that Democrats have a strong chance of winning both the House and Senate in the 2018 midterm elections, and Democrats now lead by more than 10 points on generic ballots against Republicans, polls show.

In 1992 Republicans mocked Bill Clinton for going by "Bill" instead of "William".

It was a stupid take then and it is still a stupid take today. https://t.co/n8q2qDPpxE — Juan P.E. ❄️ ???????? (@jrivera64) March 7, 2018

Ted Cruz’s attempt to make fun of Beto O’Rourke’s nickname appeared to fall flat, with many calling out Cruz on social media and noting the silliness of going after a nickname in a race where there are many more pressing issues.