"I don't go into Thursday with huge expectations other than just to have the kind of conversation that we need to start having so that we are getting ourselves on the same page as a party," Ryan told radio host Stan Milam of WBEL radio, which broadcasts in his hometown of Janesville, Wisconsin.
But some GOP members are fuming that Ryan's airing of his high profile concerns about Trump aren't helping unifying the party, but instead making the split worse.
Ryan stressed that he barely knows the billionaire businessman, telling Milam, "I assume that's what Donald wants as well. Again, we don't know each other, we talked once a few months ago on the phone, a very good conversation."
Oklahoma Republican Sen. Jim Inhofe told reporters Tuesday, "I didn't really appreciate his comments."
Inhofe backed another GOP candidates in the primary process, but said about Trump and Ryan, "I think at the time he's going to be the nominee, they're going to be working together, they have to establish a working relationship and I think they will but that's not a good way to start."
Noting that it's been one week since Trump was dubbed the GOP's presumptive nominee, Ryan later told The Wall Street Journal's Gerald Seib in an interview streamed on Facebook. "It's going to take more than a week to repair and unify this party."
After suggesting over the weekend that he would remove Ryan
as the GOP convention chair if he didn't get behind his candidacy, Trump struck a more collegial tone
in a tweet on Tuesday.
"I look very much forward to meeting w/Paul Ryan & the GOP Party Leadership on Thurs in DC. Together, we will beat the Dems at all levels!" Trump tweeted.
Ryan didn't outline specific policy areas he intended to raise with Trump, saying he didn't want to negotiate through the media. Instead, he spoke in broad terms about trying to rally around "conservative principles."
Pressed if he saw a way to "compromise" with Trump that didn't conflict with conservative principles, Ryan replied, "of course, absolutely I do."
Trump's chief backer in the Senate, Sen. Jeff Sessions of Alabama, said Ryan's move to hold back his endorsement was "a mistake."
As for the policy differences between the two men Sessions said, "many of (Trump's) opponents were advocating positions totally in synch with Speaker Ryan's positions. But Trump won."
But when fielding a question about who conservatives should vote for this fall, Ryan didn't mention Trump's name. Instead, he said it was important for "all conservatives to rally together to win this election and defeat Hillary Clinton." He stressed that with a GOP-led House and Senate there was "one more mountain to climb" in capturing the White House.
The speaker, who ran as the GOP's vice presidential candidate in 2012, appeared to warn Trump about the need to appeal to voters in purple states.
"I had some experience with the electoral college. I learned the hard lesson in 2012 on how not to win the electoral college, and we have to be a party that is broad and inclusive, principled, applies those principles to the problems of the day, offering the country better solutions and actually appeals to independents and disaffected Democrats," Ryan told the Journal.
Ryan made it clear that the process to come together is going to stretch beyond one meeting with Trump.
"We can't just pretend to be unified when we know we're not. If we fake it, then we're going to go into the fall at half strength," Ryan told radio host Michael Medved.
The top Senate Republican, Mitch McConnell, expressed confidence in Trump's chances in November, citing new state polls in several swing states showing a close contest between the GOP nominee and Hillary Clinton. Pressed about any concerns with Ryan failing to get behind Trump, McConnell demurred, saying, "you'll have to ask the Speaker about that.
Asked if he and Trump might walk out of the Thursday session with some sort of "Contract with America"-type program similar to the one drafted by former Speaker Newt Gingrich in 1994, Ryan suggested the work to unite the factions would take more time.
"I'm not sure that one meeting does that. I think it's a process that needs to begin in earnest," Ryan said, adding there are still two months before the July convention that he is supposed to chair.
Rep. Darrell Issa, who backed Rubio initially, is now a delegate for Trump to the GOP convention. He told CNN he understood Ryan as the convention chair has stayed out of the race and is doing his due diligence to work through some concerns. But he hoped Ryan and the party would come together in time for the July convention, adding, "but sooner would be better."
The speaker didn't appear to share the concerns that some Republicans raised about Trump's tax proposals that could potentially result in increased rates, saying, "I don't see that we're real far apart on that."
'Not the most important thing'
Ryan's Capitol Hill office is also doing its best to turn reporters' attention away from the marquee meeting on Thursday.
AshLee Strong, a spokeswoman for Ryan, sent a missive to the Capitol Hill press corps on Tuesday headlined "Ryan/Trump" which started out "No, not really."
Instead, the email argued that the summit brokered by Ryan's longtime political ally, Republican National Committee Chairman Reince Priebus, is "not the most important thing happening in DC this week."
The email ticked through other business on the House floor such as votes on a package of bills to combat the opioid addiction crisis.
House GOP leaders will have their regular weekly meetings Tuesday afternoon when they return to Washington after a week-long recess.
Like Ryan, many of them expected the race to last a while longer and not face questions about Trump.
Most top congressional Republicans don't know Trump and the meeting will be the first time they begin to build a relationship with the outsider candidate who will be at the top of the ticket in November. They are expected to discuss their strategy so they can go into the Thursday meeting with a unified message about the fall election, one senior GOP congressional source told CNN.
Ryan's No. 2, House Majority Leader Kevin McCarthy, who has never personally met Trump, is already officially allying himself with GOP nominee. He was listed as a Trump delegate on the slate heading to the Cleveland convention that the campaign assembled in California.
McCarthy, along with the rest of the GOP leadership team in the House, has repeatedly said he planned to support his party's nominee for president. The California Republican recently he told reporters he planned to go to the convention, as he has in past years, but at that time indicated he wasn't planning to participate as a delegate.
Texas GOP Rep. Roger Williams, who backed Cruz said when he stepped aside from the race he got behind Trump, telling CNN, "we've got one person."
Asked about the ability to bring members together after Ryan's reluctance to endorse, Williams said, "I do think it does make it tougher but that's why Thursday's meeting is going to be very important."