Speaker Paul Ryan said Thursday that he would now endorse presumptive GOP nominee Donald Trump after initially saying that he is not ready to back the billionaire businessman. The endorsement brought to an end the long-standing rift between the party’s two most influential members.

Ryan said that he is now certain that Trump will be able to successfully advance the Republican Party’s agenda.

“I feel confident he would help us turn the ideas in this agenda into laws to help improve people’s lives. That’s why I’ll be voting for him this fall,” Ryan wrote in an op-ed for the Janesville Gazette, as quoted by the CNN.  “It’s no secret that he and I have our differences. I won’t pretend otherwise. And when I feel the need to, I’ll continue to speak my mind. But the reality is, on the issues that make up our agenda, we have more common ground than disagreement.”

In response to Ryan’s decision, Trump tweeted his appreciation later on Thursday. “So great to have the endorsement and support of Paul Ryan. We will both be working very hard to Make America Great Again!” he tweeted.

Trump and Ryan spoke over the phone since Ryan’s statement early last month that he wasn’t ready to back Trump. According to a source, the decision to endorse Trump was taken earlier in the week, but Ryan kept away from revealing the discussion that took place between him and Trump.

“He didn’t give Mr. Trump a heads up. This was always going to be the speaker’s own decision on his own timeline,” the source said. “This wasn’t a negotiation. As he wrote, through their conversations he gained a comfort that they could work together on this.”

The Star Tribune reported that during an exclusive interview with the Associate Press, the speaker said that his only goal behind supporting Trump is to ensure that the party is unified and is at its full strength in the fall.

“This to me is about saving the country and preventing a third progressive, liberal term, which is what a Clinton presidency would do,” Ryan said.