Story highlights John McCain was diagnosed with brain cancer Wednesday night

The Arizona Republican underwent surgery to remove a blood clot Friday

(CNN) Sen. John McCain tweeted his thanks to his supporters Thursday morning following news of his cancer diagnosis.

I greatly appreciate the outpouring of support - unfortunately for my sparring partners in Congress, I'll be back soon, so stand-by! — John McCain (@SenJohnMcCain) July 20, 2017

"I greatly appreciate the outpouring of support - unfortunately for my sparring partners in Congress, I'll be back soon, so stand-by!" McCain tweeted