Big-time investors Chris Sacca and Fred Wilson are at odds over Twitter's future

The pressure is on at Twitter: After a disappointing first-quarter earnings statement, a lot of Wall Street analysts and Silicon Valley types have been openly wondering if Costolo will still be chief executive at Twitter for much longer.

A little over a week ago, renowned Silicon Valley venture capitalist and early Twitter investor Chris Sacca wrote a blog post called "I Bleed Aqua," explaining that while he loves Twitter, he has his own take on where the company should go that he plans on making public in the near future.

Yesterday, Union Square Ventures partner and legendary investor Fred Wilson defended Costolo in a blog post of his own - including a not-so-subtle reference to Sacca's plan to more openly talk about his vision for Twitter.

"I do not plan to be more critical of Twitter in the coming months," wrote Wilson. 

Wilson's blog post was mainly in praise of Costolo's appearance at last week's Re/code conference, where the Twitter executive fielded some tough questions, including whether he'd still be CEO of Twitter by the end of the year.

Today, Sacca took to Twitter to respond to Wilson in turn:

When reached for comment, Sacca said that he had nothing to add beyond his Twitter posts. Wilson did not reply at the time of publication.