If Rep. Joaquin Castro, D-Texas, decides to run against Sen. Ted Cruz next year, he might already have a leg up on Twitter.

Castro has been hinting at a run against Cruz, who has faced the possibility of a primary challenge after he waffled on his support for President Donald Trump, possibly making him a weakened general election candidate.

On Wednesday, the Texas Tribune’s Patrick Svitek tweeted a quote of Cruz saying “As a Cuban, I’m quite familiar with standing up to the Castro brothers,” referring to Cuba’s president Raul Castro and his late brother Fidel.

.@TedCruz on a Joaquin Castro challenge: “As a Cuban, I’m quite familiar with standing up to the Castro brothers,” but in different context

— Patrick Svitek (@PatrickSvitek) February 15, 2017

In response to that, Castro tweeted about how Cruz often avoided attacking Trump in hopes of avoiding attacks and picking up his followers if he got out of the presidential primary race.

.@TedCruz The same way you’ve stood up (down) to Donald Trump? https://t.co/waMa9pAx7t

— Joaquin Castro (@JoaquinCastrotx) February 15, 2017

Castro is the twin of Julian Castro, who was Housing and Urban Development Secretary for the Obama administration and served as mayor of San Antonio. Both are seen as glimmers of hope for Democrats in deep-red Texas.

Despite his Twitter game, Castro would still face large obstacles to beating Cruz in a state that went for Trump by more than nine points in 2016.