Paul Ryan Still Not Ready to Endorse Donald Trump It's unclear when an endorsement will be announced.

 -- House Speaker Paul Ryan declined to endorse presumptive Republican presidential nominee Donald Trump on Wednesday after senior-level Trump campaign sources told ABC News earlier today that Ryan was preparing to do so.

Speaking to reporters, Ryan said he has not made a decision about whether to endorse Trump.

"I have no timeline in mind," Ryan said at a briefing for the press in his Capitol Hill office.

It has been widely reported that Trump and Ryan haven't seen eye to eye on several issues.

The Wisconsin Republican has frequently condemned Trump's campaign, including his proposed temporary ban on Muslim immigration, which Trump has since called a "suggestion," and Trump's initial resistance in denouncing the Ku Klux Klan after former Grand Wizard David Duke said he supported Trump.

In a May 5 interview with CNN, Ryan said he wasn't ready to endorse Trump, despite the billionaire mogul's decisive Indiana primary win, which knocked out his final two GOP rivals and made him the party's presumptive presidential nominee heading into its July convention.

Trump shot back during an interview with ABC News' George Stephanopoulos that he didn't think the Republican Party needed to be unified behind his candidacy.

After much back and forth, Ryan and Trump finally decided to meet in Washington with Republican National Committee Chairman Reince Priebus also in attendance.

Trump arrived in Washington — amid a swarm of media — to make a stop on Capitol Hill at the headquarters of the Republican National Committee.

After the meeting, Ryan and Trump issued a joint statement calling for Republicans to "unite around our shared principles, advance a conservative agenda and do all we can to win this fall."

But Ryan still wasn't ready to get behind Trump.

ABC News' John Santucci contributed to this report.