Donald Trump. AP Photo/Charles Rex Arbogast Donald Trump fired back at House Speaker Paul Ryan on Thursday after Ryan said that he was "not ready" to support the party's presumptive presidential nominee.

"I am not ready to support Speaker Ryan's agenda," Trump said in a statement. "Perhaps in the future we can work together and come to an agreement about what is best for the American people. They have been treated so badly for so long that it is about time for politicians to put them first!"

Earlier on Thursday, Ryan made a move without recent precedent, telling CNN that he cannot support or endorse the real-estate magnate until he unifies the party.

"I'm just not ready to do that at this point," Ryan told CNN host Jake Tapper in an interview. "I'm not there right now."

He continued: "I hope to, and I want to. But I think what is required is to unify this party. And I think the bulk of the burden on unifying the party will have to come from our presumptive nominee."

The speaker called on Trump to "set aside bullying, set aside belittlement."

But Ryan did add that his refusal to endorse or support Trump should not be interpreted as an endorsement of Democratic frontrunner Hillary Clinton.

"No Republican should ever consider supporting Hillary Clinton," he said. "Let me make that clear."