GOP presidential candidate Sen. Rand Paul (R-KY) arrives to speak at the "Women Betrayed Rally to Defund Planned Parenthood" at Capitol Hill on July 28. (Carlos Barria/Reuters)

The first Republican debate of the 2016 presidential campaign, said Sen. Rand Paul of Kentucky, will be between him and people who “want to blow up the world.” The showdown Thursday night will pit him against opponents who will “send half a million of your sons and daughters back” to Iraq. He vowed that he will ask his Republican presidential rivals, face to face, whether they “want to always intervene in every civil war around the world.”

“I want to be known as the candidate who’s not eager for war, who thinks war’s the last resort,” Paul said on a weekend swing through Iowa. “When we fight, we fight to win, but much of our involvement has led to consequences that made us less safe. You’ll see that come into sharp distinction.”

Paul’s approach almost ensures that there will be a vigorous debate Thursday night over foreign policy, an issue that many Republicans see as a major distinction between them and Democrats. It also marks a shift back toward Paul’s roots — and, he hopes, a winning coalition of voters — after months in which he seemed to slide toward a more traditional Republican foreign policy as the Islamic State and other global dangers grew more worrisome.

The libertarian wing of the Republican base has been waiting and waiting — and waiting — for Paul to do that. Any of the declared candidates can talk tax cuts. A few, such as former Texas governor Rick Perry, can match Paul on criminal-justice reform. They all want to defund Planned Parenthood. But no one else is positioned to attack a generation of intervention in the Middle East. Libertarians want the Rand Paul who mocked former vice president Richard B. Cheney and neoconservatives to show up at the debates.

“He’s the only candidate of the 15 who has a position like this,” said Michael Hager, 23, after seeing Paul speak in a suburb of Chicago over the weekend. “I figure, hell, why not swing for the fences on this? Why not separate himself from the pack?”

Sen. Rand Paul (R-Ky.) takes batting practice Saturday with the Quad-City River Bandits in Davenport, Iowa, during the presidential hopeful’s campaign trip through Iowa. (John Schultz/Quad City Times via AP)

Paul’s potential base is larger and talkier than anyone else’s, built on the legacy of his father’s 2008 and 2012 presidential runs. When Rand Paul has moved away from that Ron Paul legacy, he has walked into a wall of flames.

He co-signed a letter sent by Sen. Tom Cotton (R-Ark.) and other senators to the Iranian mullahs, and he offered an amendment that would have upped defense spending with offsets in cuts to foreign aid. Paul insisted that he did it to forge peace. His reward: columns, blog posts, and podcasts that branded him a sellout.

“He sides with Bibi and other death merchants,” wrote longtime Paul ally Lew Rockwell, referring to Israeli Prime Minister Benjamin Netanyahu.

“The really naive people are the ones who thought that by doing things like this, Rand would win over the people who despise him,” said Tom Woods, the co-author of Ron Paul’s best-selling books.

Rand Paul’s Iowa message to the critics: Hey, lay off and wait for Thursday. “I’m one of the few Republicans who has a litany of people whose job is to be full-time critics of mine,” Paul said. “Nobody else seems to have as much sniping going on. But I think the debates will put things in sharp relief.”

The GOP’s non-interventionist voters see no other way for Paul to become relevant again. They remember how the Ron Paul phenomenon of 2007 began: with a presidential debate, hosted by Fox News in South Carolina. Paul, who was barely registering in polls, was the only Republican advocating immediate withdrawal from Iraq. Moderator Wendell Goler worried the point, asking whether the 9/11 terrorist attacks had rendered Paul’s old non-interventionism quaint and irrelevant.

“Have you ever read about the reasons they attacked us?” Paul asked Goler. “They attacked us because we’re over there. We’ve been bombing Iraq for 10 years. . . . I’m suggesting that we listen to the people who attacked us, and the reason that they did it.”

Former New York mayor Rudolph W. Giuliani, who led in national polls at the time, elbowed in and accused Paul of disrespecting the victims of the 9/11 attacks. “I would ask the congressman to withdraw that comment and tell us that he didn’t really mean that,” he said.

“I believe the CIA is correct when they teach and talk about blowback,” Paul said.

The Texas congressman decisively lost the room — and won a following. He had raised just $63,989 in the 2008 race’s first fundraising quarter. He raised $2.4 million in the second.

“Obviously, he’s not as purist as his father,” said Matt Mann, 35, after one of Rand Paul’s Davenport speeches, “but it’s a move in the right direction.”

The younger Paul’s riff on intervention is not as idealistic as his father’s. In Iowa, it started with a windup about the intractable warring of the Middle East (“Sunnis either killed the Shiites or vice versa”) and the folly of arming rebels who could easily turn on the United States. Anyone who supported “Hillary’s war in Libya” — a term he’s used for a year — was disqualified from the presidency. In an interview, Paul declined to criticize any of his Thursday-night competitors by name but sounded ready to re-litigate the National Security Agency program with New Jersey Gov. Chris Christie and former Florida governor Jeb Bush.

“Overall, opposing President Obama collecting your phone records is very popular in the Republican primary,” Paul said. “The Boston bombing, Fort Hood and Chattanooga — under all three of them, we’ve had bulk collection of records. And bulk collection hasn’t helped.”

Paul drew another distinction on the Iran deal. Two Republican rivals, Wisconsin Gov. Scott Walker and Sen. Marco Rubio (Fla.), have pledged to undo it on their first days in office. Paul, who intended to vote against the deal, would give Iran a chance to prove itself.

“I think what you’d have to do, anytime you look at any international deal, is look to see if people are complying with it,” Paul said. “It would be dependent on compliance.”

Drawing lines around his candidacy will be trickier for Paul than for his father. Sen. Lindsey O. Graham (S.C.) and former senator Rick Santorum (Pa.), Paul’s most eager Republican foils, probably won’t make the cutoff for Thursday’s prime-time debate. Cruz and Rubio, both more reliable hawks than Paul, can say they opposed strikes on Syria when President Obama floated them in 2013; Cruz was not in the Senate when it allowed the Libya no-fly zones that led to the fall of Moammar Gaddafi’s government.

There’s one more problem: getting the candidate to focus. Paul has stacks of issues, all of them designed to win over one segment of the party’s base, seemingly promoted at random at his rallies. Taking part in a full-uniform batting practice with the Quad Cities River Bandits, he swung at balls labeled “tax code,” “growing debt” and “NSA snooping.” At an outdoor event in Davenport, Paul stood between 150 people and a “14.5 percent” cutout, symbolizing his flat tax rate. He mentioned that toward the end of the speech. The next morning, at a truck stop visit 15 miles away, Paul stood next to a banner promoting the Fuel Choice and Deregulation Act of 2015. He did not mention it at all.

Paul’s frustrated supporters say they think that foreign policy is the best possible topic for the debates. In a 17-candidate field, where contenders in the high teens get called “front-runners,” they see a way for Paul to consolidate a real base. In April, for example, a Fox News poll asked Republican voters whether a nuclear Iran was a “disaster” or a “problem that could be managed.” Only 28 percent said it was manageable. But Paul, who has argued that Iran could be contained just as Pakistan is contained, has never polled close to 28 percent. Even in the less-crowded fray of 2012, 28 percent would have been enough to win Iowa.

The votes wouldn’t necessarily transfer like that, Paul said. “When you poll Iowa Republicans and you ask them: ‘Do you think we should be more involved in foreign wars like John McCain, or less involved, like Rand Paul?’ Using my name in the description, it’s 45 percent for him, 41 percent for us,” he said. “Yet we don’t get 41 percent numbers. We think that for the people who want less intervention, like I do, that this is not their number one issue. If that’s your number 10 issue, and you have nine above that, I have to compete with everyone on those other nine issues.”

The poll he cited had been taken 10 months ago. Back then, even as the Islamic State broke into the headlines, Paul played a bigger role in the GOP’s internal debates. His hope for Thursday was that some other Republican was brash and foolish enough to make him talk about war.

“We’re going to be contributing to various campaigns if they promise to attack me,” Paul said with a chuckle.