House Speaker Paul Ryan and Donald Trump will begin a conversation they hope will end with a unified Republican Party when the presumptive GOP nominee visits Washington on Thursday.

But lingering concerns over Trump’s tactics, tone and chances against likely opponent Hillary Clinton have left major questions over if and when a divided party still reeling from a nasty presidential primary can come together anytime soon.

Ryan, who caused waves last week when he said he is not yet ready to back Trump, will meet with the presidential candidate and Republican National Committee Chair Reince Priebus at 9 a.m. at the RNC headquarters on Capitol Hill.

“What we are trying to do is to be as constructive as possible, to have a real unification,” Ryan told reporters Wednesday.

“To pretend we’re unified without actually unifying, then we go into the fall at half strength,” he added. “This election is too important to go into an election at half strength.”

Ryan and Trump have met in person only once before in 2012, and spoke over the phone in March. Ryan has said he would step down as chair of the GOP convention in July if Trump asks him to.

Following Trump’s meeting with Ryan and Priebus, the real estate mogul will meet Republican leaders in both the House and Senate, including Senate Majority Leader Mitch McConnell. Ryan will also attend the House leadership meeting.

A spokesman for Missouri Sen. Roy Blunt told NBC News, “The senator will use the opportunity to remind him that what we say and how we say it matter in making it clear that our common goal is defeating Hillary Clinton and guiding America in a new direction.”

Trump said it was his goal to unite the GOP after rivals Ted Cruz and John Kasich ended their 2016 bids last week. But since becoming the party’s de facto nominee he wasted no time in engaging in the kinds of rhetoric many in his party had feared, continuing to accuse Clinton of “playing the woman card” and attacking her and her husband for the former president’s sex scandal.

In an interview on Fox News on Wednesday, Trump said it will be “great” if he makes some kind of deal with Congressional leaders. “And if we don’t, we will trudge forward like I’ve been doing and winning all the time,” he said.

The GOP’s internal strife was apparent at a House Republican conference meeting on Wednesday, sources in the room told NBC News. Six GOP House members openly expressed their frustrations with Ryan for his hesitancy to support Trump. Others said they now felt pressure to choose sides – Trump or Ryan.

Other members also expressed support for the highest ranking Republican in the House.

Ryan met with Trump supporters in the House later on Wednesday, with attendees telling NBC News it was a positive meeting where the Wisconsin Republican laid out the some policy differences he has with Trump – among them how the role of the Executive Branch balances with the Legislative Branch.

But despite Ryan’s sit down with Trump, some Congressional Republicans worry that the longer the speaker waits to give a full-throated endorsement of the party’s presumptive nominee, the more problems it will cause them in November.

Rep. Mike Kelly, R-Pennsylvania, a Trump supporter, told NBC News, “Look, when something bad happens to you it’s okay to grieve, but after three days it’s time to rejoin the living.”