WASHINGTON (AP) -- Just days into his tenure as the presumptive Republican presidential nominee, Donald Trump is brushing off a stinging rebuke from the GOP's top elected official while vowing to unite a fractured party.
House Speaker Paul Ryan's declaration that he wasn't ready to support Trump sent shockwaves through the very Republican establishment the New York billionaire is asking for help in transitioning from the primary season into the general-election campaign.
"I'm not there right now," Ryan told CNN on Thursday when asked about backing Trump. "And I hope to. And I want to. But I think what is required is that we unify this party."
Even in an election season that has exposed extreme and public divisions within the GOP, Ryan's decision to withhold his support from Trump was extraordinary. Second in line to the presidency, the House speaker was not alone in turning his back.
Both Mitt Romney, the Republican presidential nominee in 2012, and former President George W. Bush said they do not plan to attend the July national convention where Trump will be formally nominated.
Trump ignored the rebukes during a Thursday night appearance in Charleston, West Virginia, addressing Ryan's decision only in a written statement issued earlier in the day.
"Perhaps in the future we can work together and come to an agreement about what is best for the American people," Trump wrote. "They have been treated so badly for so long that it is about time for politicians to put them first!"
Trump's advisers have begun conversations with the Republican National Committee on coordinating fundraising and tapping into the committee's extensive voter data file and nationwide get-out-the-vote operation.
RNC officials sent a draft of a joint fundraising proposal to the Trump campaign on Thursday that details how they would divide donations between the campaign, the national committee, the national convention committee and several state parties. The agreement, standard practice in modern-day campaigns, is expected to be finalized in the coming days.
Trump on Thursday named a finance chairman, Steven Mnuchin, a private investor with ties to New York and Hollywood who has never led a major political fundraising team. Many major GOP donors have never heard of him --- or even know how to pronounce his name (muh-NOO-chihn). Like his new boss, Mnuchin has a record of giving both to Republicans and Democrats, including Democrat Hillary Clinton during her 2008 presidential run.
The cool reception from Romney, Bush and Ryan sends an unmistakable signal to their fundraising networks, which include most of the GOP's best-connected donors.
"You might have a lot of these donors sit on the sidelines," said Spencer Zwick, who led Romney's fundraising efforts and now serves as Ryan's national finance chairman.
Trump has not yet ruled out accepting public financing for his general-election effort. Taking public money would dramatically limit how much he can spend this fall.
The billionaire acknowledges he would have to sell some of his holdings to muster the hundreds of millions of dollars for a general-election bid, something he says he doesn't necessarily want to do.
Meanwhile, Ryan is positioning himself to play a central role in helping to protect vulnerable House and Senate candidates heading into the general election. The speaker has long been working on an "agenda project" that could give Republicans something to run on independently from their presidential nominee.
"He's constantly out there talking about his agenda," Zwick said of Ryan, adding: "Many people aren't sure what the Trump agenda is yet."
Trump and Ryan have publicly clashed in the past. Ryan rebuked Trump for plans to bar Muslims from the country and when he was slow to disavow former Ku Klux Klan leader David Duke. Trump told a crowd in South Carolina in February that Ryan doomed the GOP presidential ticket four years ago by saying entitlement programs need reform.
Ryan acknowledged the mogul had "tapped into something in this country that was very powerful. And people are sending a message to Washington that we need to learn from and listen to."
"But at the same time, now that we have a presumptive nominee who is going to be our standard-bearer, I think it's very important that there's a demonstration that our standards will be beared," Ryan said.