WASHINGTON — Sen. Rand Paul was in the middle of one of his trademark takedowns of the "right-wing hawks" in his party who "have never met a war they didn't want to get involved in," when he suddenly paused and began grinning.

"There was a funny article the other day in Mother Jones — did you see it? About one of my colleagues?" he asked.

He was trying to do the polite, senatorial thing by not mentioning his "colleague" by name. But when his vague prompt was met with a blank look during an interview with BuzzFeed, he scrapped the pretense of diplomacy and charged forward.

"It ranked the different countries on how eager Sen. [John] McCain wanted to be involved [militarily]," he explained, not even attempting to contain his amusement. "So, like, for getting involved in Syria, there's five Angry McCains. For getting involved in the Sudan, there's two Angry McCains. And there's a little picture of him. You know, he was for getting involved to support [former Libyan president Muammar] Gaddafi before he was for overthrowing Gaddafi. He was for supporting [former Egyptian president Hosni] Mubarak before he was for supporting the Muslim Brotherhood before he was for supporting the generals."

Not long ago, the Washington grown-ups who run the Republican Party would have dismissed the junior senator from Kentucky making cracks about an establishment pillar like McCain as little more than the goading of a gadfly. But over the past two weeks, it has become clear that Paul's brand of Republicanism has spread deeply within his party. He successfully rallied a bipartisan coalition of lawmakers against a military intervention in Syria; thoroughly embarrassed Republican leaders who supported the air strikes; and temporarily elevated himself to the role of de facto foreign policy spokesman for the GOP. When President Obama took his case for war to the American people in a primetime address this week, it was Paul who delivered the unofficial Republican counterargument in a series of interviews and a widely covered speech.

Paul, in short, is winning. The Syria debate marked the first time since House Republicans tried to keep America out of the Kosovo conflict in 1999 that a libertarian approach to foreign policy seriously challenged the GOP's old-guard caucus of hawks. And this time, the libertarians came out on top. In this context, his McCain mocking didn't come off as mischievously trolling for a couple headlines — it seemed a little like punching down.

Don't expect Paul to stop swinging. The plainly ambitious libertarian and prospective 2016 presidential candidate has big plans for his party and his country — plans that will require winning a lot of arguments, defeating a lot of opponents, and effectively conquering a GOP establishment that often treats him like a tumor that needs to be surgically removed. He is always on offense: Over the course of his 20-minute interview with BuzzFeed, he took swipes — with varying degrees of force — at Bill Kristol, Samantha Power, Chris Christie, President Obama, President Bush, Cory Booker, humanitarian interventionists, and pro-war Christians (to name a few).

One of his favorite targets — and the one that most delights the political press — is the Bush-era army of neoconservative Republicans who championed the Patriot Act and led the U.S. into war with Iraq. (Paul believes the U.S. should only use military force when the country's national security is directly at risk.)

"So many of the neocons in our party, they think they're the great defenders of the military. They think, Oh, the soldiers must love me because I want to be involved in war," Paul said, before criticizing the assumption that members of the military are eager to fight. "They will, they volunteered, and they're the most patriotic of our young people. But they're not excited about war. They want to go to war if it's the thing they have to do to defend our country."

When asked about the misguided prediction Kristol made earlier this month that only five Senate Republicans would side with Paul in opposing the Syria strikes, the senator interjected to ask, "You saw my response to him?" (Paul had challenged his neoconservative nemesis to visit a military base and talk to GIs before assuming popular opinion was on his side.) Satisfied that his jab had properly penetrated the media sphere, he proceeded to lay out where he believed the votes stood in the Senate. His estimate that 20 or 25 Republicans would vote no was probably modest: The latest unofficial count suggests the number could top 30.

It would be easy to mistake Paul's successes this year — from his campaign against the Syria intervention to his attention-grabbing filibuster against U.S. drone use to the public backlash against the types of domestic surveillance programs he'd been warning about for years — as some sort of permanent sea change in American politics.

Paul knows better. He acknowledges that his ideas have benefitted from "a degree of partisanship" on the right. Republicans, after all, might not be quite so skeptical of executive power, or outspoken against the ever-expanding surveillance state, once one of their own is in the Oval Office. What's more, he spent enough time watching the GOP ignore, then laugh at, then co-opt, then abandon his father's libertarian platform to recognize the fickleness that can define political parties.

But he is also adamant that his agenda's growing popularity is a product of the times: "There's a big transition in the Republican Party, but also in the public. People are right about the public being war-weary. They're right."

Meanwhile, his recognition that the fight is nowhere near won seems to fuel his apparently endless appetite for political combat.

Paul often aims at the president, using his nonstandard political philosophy to find fresh critiques of the administration. He laid into the "Samantha Powers of the world" who foolishly want to "send troops to feed people" in remote countries all over the world. And he called out Obama himself, whose rationale for putting armed forces at risk in Syria he finds indefensible.

"The other day, when [the president] came to lunch, [he said] that we're not facing very many direct threats in this world to the United States... and so you're going to have to be involved in much more ambiguous situations," Paul recalled. "I'm guessing he wouldn't use that term in public but that's the term he used with us."

Paul also finds plenty to dislike in his own party's approach to beating the war drum — particularly the theological overtones of the Bush years. In a strikingly candid speech last year at the Value Voters Summit, Paul, a Presbyterian, cited his religious beliefs while declaring, "I'm not a pacifist. But I do think it unacceptable not to hate war."

He elaborated to BuzzFeed: "I think some within the Christian community are such great defenders of the promised land and the chosen people that they think war is always the answer, maybe even preemptive war. And I think it's hard to square the idea of a preemptive war and, to me, that overeagerness [to go to] war, with Christianity."

In the world of politics, though, Paul seems preternaturally comfortable at war. One particularly instructive example is his feud with New Jersey Gov. Chris Christie. Earlier this summer, Christie accused the libertarian of prioritizing "esoteric, intellectual debates" over national security — a harsh attack that seemed to come out of nowhere. Though Paul didn't instigate the spat, he happily stretched it out over several days, answering every interviewer's question about his aggressor, and memorably referring to the governor at one point as "the king of bacon." The fight fizzled when Paul invited Christie for a beer (he declined), but he has never quite let it go.

When BuzzFeed asked him this week whether he was surprised Christie didn't engage the Syria debate more directly by staking out a position, Paul paused for a beat before offering a cutting response.

"I guess I didn't really notice or think about it that much," he said.