Republicans who supported Donald Trump because they wanted to change the party's approach to immigration are starting to wonder if they bet on the wrong man. But Republicans who backed Trump to shift the party's hawkish foreign policy in a more realistic direction ought to be sure they made a bad gamble.

They should have bet on Rand Paul.

Yes, it was enjoyable to watch candidate Trump dispatch some of the GOP's loudest hawks — in places like South Carolina, no less — while declaring the Iraq war a "big, fat mistake." He went on to defeat Hillary Clinton, whose disastrous intervention in Libya and clamoring for a greater U.S. role in Syria demonstrated how little she learned from her Iraq vote, while also swearing off wars for regime change in the Middle East — a relative rarity for a Republican.

There's even a study making the case that Clinton's support for bipartisan military adventurism compared to Trump's relative restraint helped cost her the White House, a possibility omitted in the endless relitigation of the campaign.

Since taking office, however, is there a single area where the United States is involved militarily where President Trump hasn't escalated compared to former President Obama (whose own dovishness is greatly exaggerated)?

It's been bombs away in Syria. More bombing as part of an indefensible Yemen policy. We're adding troops in Afghanistan, a war that has now lasted longer than World War II after a just military response to the 9/11 terrorist attacks deteriorated into an impossible nation-building mission. Trump's commitment to diplomacy with Iran appears to be hanging by a thread.

North Korea can't entirely be pinned on Trump, as the rogue state is genuinely behaving in a reckless and belligerent fashion while the failures to contain its nuclear ambitions long predate the current administration. But has any previous president acted as Kim Jong Un's verbal sparring partner?

It could be worse, sure. Yet recent events have also reminded us things could have been better — with Rand Paul.

The Kentucky senator recently challenged fellow members of Congress to reclaim their constitutional war powers by voting on his amendments that would sunset existing authorizations for using military force. "If you think we should be at war with Afghanistan, vote for it," Paul said during the Senate debate. "If you think we should be at war in Yemen, come down to the floor and vote for it." Paul's point is that these authorizations of force have been used as a legal pretext for military actions in seven countries, some of them under conditions remote from the circumstances when Congress originally passed them. The Kentucky Republican is adamant that Congress take responsibility for American wars.

"My vote is on whether or not we should vote on whether we should be at war. So for those who oppose my vote, they oppose the Constitution," he added. "They oppose obeying the Constitution, which says we are supposed to vote."

"They're going to say, 'No, I refuse to vote on any of these wars,'" Paul said of colleagues who were going to vote against his amendment. "We don't want any responsibility."

Paul is right. Thirty-five other senators voted with him to continue debate, while 61 voted to end it. "Candidate Trump repeatedly argued that the Afghan war was a disaster and should end," Paul said. "Once in the White House, however, President Trump is escalating the war in Afghanistan just as President Obama did."

Ron Paul's son has been one of the most consistent opponents of preventive war in Congress, keeping military action a weapon of last resort. He's also been more creative than Trump in trying to mainstream "America First," such as when he suggested cutting foreign aid to pay for hurricane relief for Americans. "I say not one penny more to countries that are burning our flag," Paul has said.

The younger Paul made his share of mistakes as a Republican presidential candidate in 2016. His measured approach failed to excite libertarians, while the core reason for voting with him was his comparative libertarianism. He couldn't compete with Trump's television coverage or Ted Cruz's ability to tell the base whatever it wanted to hear.

At the same time, Republicans who ought to know better were charmed by Trump's star power, making excuses for the reality TV star's hopelessly muddled foreign policy — let's stay out of Iraq but also not leave without taking their oil! — while holding Paul to impossibly high standards.

It's too soon for Republicans to dump President Trump. But when they want a new foreign policy, they'll need to stand with Rand.