Tom Rogan is a foreign policy columnist for National Review, a domestic policy columnist for Opportunity Lives, a former panelist on "The McLaughlin Group" and a senior fellow at the Steamboat Institute. Follow him on Twitter @TomRtweets.

(CNN) You would normally associate Republicans with lower spending. But not when it comes to the next president of the United States.

Donald Trump has big spending ambitions. He wants to spend $550 billion updating the nation's creaking infrastructure. Alongside major tax reductions, Trump also wants big boosts to defense spending . That's not all. The President-elect has also pledged not to reform America's entitlements system of Social Security (pensions and income support) and Medicare (health care for the elderly).

That's a big deal.

As the non-partisan Congressional Budget Office regularly points out, entitlements are the fundamental driver of the national debt. And while Trump says he'll cut spending in other areas, these savings would be drops in the entitlements ocean. Even conservative experts say Trump's current plan will add $4 to $5 trillion to the debt.

This has many Republicans in Congress worried. Perhaps none so more than the top congressional Republican, House Speaker Paul Ryan. Ryan's number one priority is reducing entitlement spending. Like many conservatives ( myself included ), Ryan believes that reforming entitlements is key to the nation's better future. Absent such reform, young Americans face a bitter future of ever-increasing taxes and interest rates, alongside ever-decreasing benefits.

Still, Trump will be president. And subject to an override of his presidential veto, only he will be able to sign bills into law. Thus, we must ask, will Trump and Ryan be able to find compromises? Recent history tells us to be wary.

For one, Ryan and Trump are seemingly not fond of one another. The speaker was notably hesitant to endorse Trump during the campaign, and the President-elect publicly criticized Ryan on a number of occasions. But that's not all. Seeking to expand Republican appeal in inner cities and across changing demographics, Ryan will likely seek to balance Trump's more populist impulses. But if, for example, Ryan stands up to Trump on an issue like immigration reform or trade protectionism, it might spark a far broader GOP civil war.

After all, Trump might be the Republican king, but he is not the Republican oracle.

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While Trump has won the presidency for Republicans, many conservatives remain deeply unsure of the President-elect's character and proposals. Even Trump's closest advisers are aware that Ryan cannot be purged without consequence. Trump's appointment of Reince Priebus -- a close Ryan ally -- as his chief of staff, signifies that reality.

But this isn't just about Ryan. It's about the Republican identity in general. And Ryan isn't alone. Senate Republican leader Mitch McConnell also has his doubts about Trump. Moreover, both Ryan and McConnell lead senators and representatives who face election in 2018. And while Trump won by securing many Democratic votes in states like Pennsylvania, congressional elections are not presidential elections. Republican primary voters like to punish congressional candidates they believe are spendaholics.

The obvious question, then, is what will happen come next year?

I think there are two basic possibilities.

First, Trump and congressional Republicans might reach a deal. Trump loves to deal, so who knows... Consider the possibility that Ryan-style Republicans support Trump's spending plans in return for entitlement reform.

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Alternatively however, Trump might refuse to negotiate and instead rely on Democratic Party votes to get his spending plans into law. And if the latter occurs, the GOP is heading for a schism. Mark my words: Many Republicans are now giving Trump the benefit of the doubt. But if they believe their small government ideals are being sacrificed, they will break from him.

All this speaks to something broader.

Ultimately, the GOP might look strong on paper, but below the surface it is roiling with tension. The divisions in contemporary conservatism were on very public display during the primaries (Pat Buchanan and I encapsulated it on "The McLaughlin Group ").

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At the moment, the optimism of a surprise victory is keeping the GOP buoyant. But when Trump becomes president on January 20 and policy is on the table, all that will change. And if no side budges, the Republican Party may split into a Trump-populist camp and the traditionalist-conservative camp.

Democrats who are mourning right now might soon have reason to smile.