The three most libertarian members of Congress are, unsurprisingly, good friends and allies. Sen. Rand Paul (R–Ky.), Rep. Thomas Massie (R–Ky.), and Rep. Justin Amash (R–Mich.) team up constantly on often-lonely crusades to restrain federal spending, rehabilitate constitutional governance, and remove U.S. troops from far-flung conflicts.

The two congressmen were loyal footsoldiers in the senator's star-crossed run at the 2016 GOP presidential nomination. (Massie's story about canvassing for Paul in Iowa is one of the most colorful explainers for how the Tea Party movement mutated into Trumpism.) In 2020, Paul is firmly on the sidelines, as is Massie ("I am absolutely ruling out a run for any office in 2020 as a big-L Libertarian," the congressman told me last summer), which leaves Amash, who is currently weighing his third-party options.

Paul last fall took the unusual step of endorsing Libertarian candidate Gary Johnson in his New Mexico Senate race against the eventually victorious Democratic incumbent Martin Heinrich and the GOP political newbie Mick Rich, despite the arm's-length relationship over the years between Johnson and the Paul family. So when I interviewed the senator about Afghanistan on Sirius XM Insight's Stand UP! with Pete Dominick Wednesday, I asked whether he would encourage Amash to run and/or consider supporting an Amash campaign.

"Well, you know, it's sort of a weird thing," Paul began. "My dad was a Libertarian candidate in 1988, and I supported him, but it has been difficult, because through the years there hasn't been enough momentum gained to show electoral progress. So, like, in some Senate races, I've actually tried to discourage the Libertarian, because I think they draw enough votes from the Republican, who often is a libertarian. We had a race in Virginia not too long ago where I thought the Republican was more libertarian than the Libertarian, who wanted…[to] raise the gas tax and put GPSs on everybody's car to monitor their driving, which didn't sound very libertarian.

"So I don't know," Paul continued. "I like Justin Amash a lot. I think he and Thomas Massie are the leading lights of the U.S. Congress as far as the libertarian perspective. You just have to decide to what is your end, because the electoral prospects don't look that good."

In terms of President Donald Trump—who Paul has been trying to influence, especially on foreign policy—don't expect the senator to back any challenger from the other major party. "As far as trying to end war or do some of the things that we want to do as libertarians," he said, "we have a better chance with, I think, a Trump than any of the ones on the Democrat side."

Speaking of ending war, here is an edited portion of our conversation covering that lamentably evergreen topic:

Welch: [A]lmost from the beginning [of your Senate career], you have used the formulation in speeches and also in bills of, "Hey, it's time to declare victory in Afghanistan and bring our troops home." Can you give a sense of how the progress of that concept…has evolved over time?

Paul: Well, you know, it's too slow for my taste—I think we should have been gone years ago. And I think that there is some progress, but it's very, very slow.

There are two important pieces to the puzzle that are improvements. We have a president—the first president, really—to say that the war has long been over, there is no military solution, he's bringing the troops home. And President Trump has said that several times. The problem is that several of his advisors that he has appointed don't necessarily agree with him. So they either countermand his sentiments or talk him into delaying actually ending the war.

The other thing that I think has happened over time—and this is sort of both positive but also sad at the same time—is that you can't meet a general anywhere in the Pentagon who believes there is a military solution to the Afghan war. That's the main question I harangue them with when they come up to Capitol Hill to testify before our committees: I say, "Is there a military solution?" And they all admit there is none. There's been mission creep that's now nation-building, but they all admit no military solution.

My follow-up question is, "Then I don't want to send my kid, your kid, or my nephew to Afghanistan, because if there is no military solution, what is one more death going to do over there?" But there are still a number of people who are of what I call the Vietnam village strategy—take one more village and we'll get a better negotiated settlement.

I'm of the belief we need to declare victory and come home, because…it's a mess now, but it will be a mess when we come home, too. And we just need to acknowledge that our original mission was to go after those who plotted or attacked us on 9/11, and there's frankly none of them left. I asked the secretary of state this not too long ago, "Tell me who's left. Tell me their names, and then we'll talk about whether you have permission to stay there to get a certain person." There's no name left….We're talking about forces that are associated with forces that are associated with forces that are associated with somebody else. It's so tangential to have any link to 9/11 that it really doesn't exist.

So I don't know. I'm encouraged that the president is listening, but I'm discouraged that when we talked about it recently the Senate voted 77–23 to remain indefinitely.

Welch: A lot of the Democratic field running for president…many of them have been saying, pretty strongly, things that sound like Rand Paul in terms of revisiting authorizations of the use of military force—ending them, as you have advocated—and bringing troops home. But even yesterday, I think, Mayor Pete Buttigieg said, "Yeah, we should totally come home from Afghanistan just as soon as we can make sure that they're not going to ever hurt us again, or commit terrorism again."

Paul: And my response to that is if we're going to wait until there's nobody left with a suicide vest in the Middle East or around the world, we'll wait forever. And there's some argument that the longer you stay in their countries, the more likely they are to have suicide vests and to remain.

But the problem with some on the left is, some of them are pretty good on Afghanistan, some are pretty good on Yemen. We have allied with Bernie Sanders and others on saying we shouldn't be involved in the Yemen war. And yet some of these people who have good instincts on Afghanistan and Yemen are now so bellicose on Russia that you can see them actually wanting to butt heads, even militarily, with Russia. So it's sort of a weird mix, and not a consistency.

But the recent vote on telling the president that he…did not have congressional approval for the participation in the Yemen war was historic. Even during the height of the unpopular Vietnam war, we never had both houses tell the president that he couldn't do what he was doing. This was a remarkable thing that happened, and I think underreported by the media because the media is so consumed with talking about Russia this, Russia that, Paul Manafort this and that. But they really lost a great news story, and that was both houses of Congress told a sitting president that he couldn't be at war. He vetoed it, but it's still historic in the sense that it's never happened before.

Welch: Do you foresee there becoming an ability to overturn vetoes like that going forward? Is there momentum on the side of people who are like, "Hey, we should check the Forever War"?

Paul: Well, you know, the president's statement in his State of the Union that great nations don't fight perpetual war is right out of the libertarian playbook, right out of libertarian lingo, and could be at any one of our meetings when libertarians talk about less intervention and less war. The sad thing is Congress really isn't there….

I know you've seen and published some of this polling that the people overwhelmingly, maybe over 60 percent of people of all different parties, think it's time to come home from Afghanistan. But we're not there in Congress. In fact, oftentimes things that are pretty popular with the public are completely the opposite with Congress. So that's the disappointing thing, is that Congress doesn't reflect the will of the people that well.

Welch: I have a juvenile image in my mind of you and Lindsey Graham in the parking lot of a golf course, kind of hitting your golf clubs against your hands, looking at each other warily, waiting to see who is able to bend the president's ear on an issue that both of you care about a lot and totally disagree with one another on, which is foreign policy. Can you characterize…what does the process look like by which you are trying to remind the president of the instincts that you like of his foreign policy, and how do you step in between the conversations with the hawks that are surrounding it?

Paul: I can give you an example. I was in the Oval Office with the president and five or six hawkish senators. They had gotten a meeting to try to persuade him that they needed to stay in Syria, that the new mission in Syria needed to be to stay until the Russians leave, until the Iranians leave. Totally unrealistic sort of mission, and really nothing related to the original mission, which was the defeat of ISIS. And so they're hectoring him to stay. He's pushing back. But me being in the room helped him to have an ally, because he had no allies, and that's a real problem. The five senators that had gotten the meeting with the president didn't invite me. I got invited by somebody else, or I had a meeting with the president before them, so it worked out perfectly that I was in the room. But I'm the only one defending the president, as well as the president defending himself.

But I think that's the hard part is, is that while the president's instincts are good on ending these wars, the capital is swarming with this bipartisan 70-year consensus for war and for intervention, and that we should always be involved everywhere around the planet. And it's just overwhelming.

So I think that it's great that his instincts remain strong, and I think he could do something historic like ending the war, and I actually think it would help his political prospects. Because I think not only is there a peace dividend to a country not spending $50 billion a year in Afghanista—and he uses the terminology of that dividend, that $50 billion that he thinks we're wasting in Afghanistan all the time—that not only is there a peace dividend, I think there is a political dividend in the sense that I think there's an independent swath of the public that does want to come home from Afghanistan, and would see it as a candidate that they could support if they can get somebody to finally end a war.

Welch: You've talked about the president's instincts as kind of being in the right direction, but are you not alarmed by more of a bellicose approach, even as recently as this week or last week, with tightening sanctions in Iran, for example? And then more immediately in our backyard, towards Venezuela and Cuba, kind of a more buttinsky approach locally than maybe he's talked about in far-flung areas?

Paul: I think it's a mixed bag. I think that Afghanistan is such an almost hopeless cause, without really any foreseeable solution, that everybody's heading in that direction and the president's already there. He sees that the Iraq war was a mistake, a regime change destabilized the Middle East. He doesn't necessarily see Iran that way.

I see Iran the same way, that if you go in militarily and topple that regime, one, it's a much bigger country than Iraq, more populous with more weaponry, and I think it's a bigger disaster. And I don't think anybody is going to be able to sell this crazy Cheney notion [that] they're going to greet us as liberators. But the administration doesn't really see it that way, and they are much more bellicose.

So when [Secretary of State Mike] Pompeo came to our Foreign Relations Committee a week ago, I asked him point blank, "You've named the Revolutionary Guard, all of them, as terrorists. Is this a pretext? Is this a justification? Do you believe you have the authority under the 9/11/2001 proclamation to go to war with Iran without asking Congress?" And he hemmed and hawed and said, "Well, you know," he says, "I'll leave that for the lawyers." And I said, "Really? This is a major constitutional principal here. We're not talking about some bizarre, esoteric part of the law. We're talking abut whether or not you can go to war without the permission of Congress." And he hemmed and hawed, so I finally told him, I said, "You do not have our permission. The Congress has not given you the authority." Because that's crazy for people to believe that we would allow any president the power just to begin a new war.