Ask Congress’ top two leaders about each other, and you’ll hear all the expected pleasantries — on the surface.

When I asked Speaker Mike Johnson about Senate Majority Leader John Thune at a Blue Light News Live event Tuesday, he was quick to praise the South Dakotan as a “principled” and “experienced” counterpart. He called Thune a straight shooter and spoke graciously about a recent dinner they’d shared with their wives.

Thune, in turn, commended his “strong working relationship” with Johnson in a “Meet the Press” interview earlier this month and said he was ready to give “deference to how he runs the House.”

Dig a little deeper, though, and it becomes obvious that all is not well in cross-Rotunda relations at the moment.

On fundamental questions of legislative strategy, Johnson and Thune remain at loggerheads as Trump prepares to take the oath of office — risking delays in enacting President-elect Donald Trump’s agenda and hinting at potential trouble in what’s quickly shaping up to be one of the most important relationships in Washington.

Both men have separately suggested, in blunt terms, that more needs to be done to get Republicans in the House and Senate singing from the same song sheet as Trump prepares to lead the choir.

“We intend for the House to be the leader on this, because that’s the way it’s designed to work,” Johnson told me, laying out the challenges of his super-slim majority and “much more diverse caucus.”

Thune suggested to NBC it was the Senate that would need to lead: “He’s got a lot of folks that are headed in different directions,” he said, adding that the House “will need to be … working closely as a team” to deliver on Trump’s sweeping agenda.

Right now, that teamwork isn’t happening. Not by a long shot.

Despite Trump endorsing Johnson’s pitch for “one big, beautiful” domestic policy bill that packages border security and energy measures together with tax cuts, Thune and his conference have refused to get fully on board. They’re moving forward with their own budget blueprint, allowing for an initial “skinny” border bill, leaving the rest for later.

And after Johnson sketched out a plan to raise the federal debt ceiling as part of that one-bill effort — writing it into the budget reconciliation procedures Republicans will have to use to avoid a Democratic filibuster — Thune balked.

In private conversations before the holiday break, I’m told, Thune told Johnson his plan would have trouble passing given just how averse some hardcore conservatives are to ever raising the borrowing cap.

Johnson marched the idea forward anyway — only for Thune to pour cold water on it this week, this time publicly: He told POLITICO’s Jordain Carney on Monday Republicans have no plans to include the debt ceiling instructions in their own budget blueprint.

Surely, inter-chamber rivalries are nothing new on Capitol Hill. Even under unified GOP control, House conservatives have long scorned Republican senators as moderate squishes, while those same senators chortle at the House hard-liners’ pie-in-the-sky policy ambitions.

Yet the stakes right now could hardly be higher, with Trump’s agenda hanging in the balance and neither Johnson nor Thune fully yielding in ongoing strategic debates. While both men say they have a good rapport, tensions have trickled down, with their inner circles each beginning to snipe at the other side.

Thune allies, for instance, gripe about Johnson backing away under pressure from his members after, they say, initially endorsing the two-track approach. Johnson allies, meanwhile, insist it’s Thune who had gotten out over his skis — and that senators, who are used to calling the shots, are just sensitive about having their strategy dictated by a closely divided House.

“It is interesting that no one has just conceded to the other,” Brendan Buck, a former top staffer to speakers John Boehner and Paul Ryan, told me. During the first Trump term, he noted, “we were aligned on the strategic question.”

Buck was quick to add, “I also don’t think that it means these folks can’t work together.” But they have to start working together — and, from Trump’s perspective, it needs to happen yesterday.

This time eight years ago, Republicans under Ryan and then-Senate Majority Leader Mitch McConnell had not only already decided to prioritize an overhaul of the Affordable Care Act, they had adopted the budget blueprint to make it possible.

Same went for Democrats after Joe Biden’s election in 2020: Speaker Nancy Pelosi and Senate Majority Leader Chuck Schumer were in lockstep (at least at first) with White House plans to quickly pass a massive pandemic-era stimulus bill, followed by a bigger domestic policy swing. They had their budget in place by Feb. 5.

Under the best case scenario laid out by Johnson this week, it will be late February before Republicans find themselves similarly situated this time — and even then, the one-bill-versus-two-bill question might not be settled.

The inability to answer central strategic questions now foreshadows much bigger problems ahead. When lawmakers actually put pen to paper to write the tax and border bills, a whole host of other, finer-grained but just as politically sensitive disagreements will arise, making the Thune-Johnson working relationship essential.

That’s especially true given Trump’s lack of distinct policy preferences and his obvious reluctance to play referee between the chambers — as became clear in recent weeks as the GOP flip-flopped between the one-bill and two-bill plans while struggling to deal with Trump’s demand for a quick debt limit hike.

Part of the challenge is that Johnson and Thune don’t have a long working relationship — or much of a relationship at all. Beyond hailing from different chambers, they’re products of different generations and different styles of Republican politics.

They also secured their leadership posts in very different ways — with Johnson hugging Trump close, while Thune mastered the inside game with fellow senators who relish their independence. Now they’re both learning the ropes as they go, leaving little time for get-to-know-you pleasantries.

At the same time, those close with the two men say they’re cut from the same cloth in some important ways. They’re known as honest brokers who are trusted by Republicans of different ideological bents — not backstabbers or schemers. They’re both calm, level-headed and inquisitive, not preachy firebrands.

And even as they’ve made their clashing positions known publicly, the two have been careful about not slandering the other, and aides say they’ve tried to give each other space to manage their own members. That would explain why Thune suggested to reporters on Tuesday that a one- or two-track strategy would work, while Johnson softened his push for handling the debt ceiling in reconciliation — even though each has members who continue to firmly disagree.

Yet they’re clearly in competition when it comes to winning Trump’s ear. I took note last month when Thune showed up at the Army-Navy football game after Johnson announced he planned to use the opportunity to lobby Trump on his reconciliation strategy. Conversely, Johnson used an audience with Trump on New Year’s Day (without Thune present) to persuade the president to back the one-bill plan.

And as Johnson made clear on stage with me Tuesday, that jockeying is going to continue, both in public and in private.

He described how he personally wrote lengthy texts to Senate Budget Chair Lindsey Graham (R-S.C.) and Sen. Ted Cruz (R-Texas) — both fans of Thune’s quick-hit approach to a border bill — to explain his complicated math problem.

“I have a much more complex decision matrix than the Senate does,” he said. “And sometimes I feel like that may be underappreciated by some of our colleagues in the other chamber.”

You hear that, Mr. Leader?