Republican presidential candidate Donald Trump speaks to the crowd in the overflow room after a town hall meeting in Derry, N.H., on Aug. 19. (Brian Snyder/Reuters)

He has crashed Wisconsin Gov. Scott Walker’s show in Iowa, knocked former Florida governor Jeb Bush off course in New Hampshire and sucked up most of the political oxygen this summer.

Now Donald Trump is headed south.

With the South poised to play it most central role yet in a GOP presidential primary process, candidates such as Sen. Ted Cruz (Tex.), Walker and former Arkansas governor Mike Huckabee — all of whom have publicly staked their campaigns on strong showings in the region — will undoubtedly be eyeing a “Donald J. Trump for President Pep Rally” Friday night in Mobile, Ala.

Trump said Wednesday night that that event was switching venues, from a civic center to a football stadium, because he now expects an attendance of 30,000 to 40,000.

Alabama’s governor on Monday backed Ohio Gov. John Kasich (R) for president, and a string of presidential contenders are visiting the state this month. But in conversations from Tennessee to Arkansas, and deep in the heart of Alabama, it is Trump who has been on the lips and minds of voters — even those who showed up to events for another candidate.

At a Ted Cruz rally in Alabama last week, the senator fired up several hundred supporters, evoking God and making liberal use of the word “y’all.” After he spoke to voters, voters spoke of Trump.

“They loaded up on him,” Jim Banks, 70, of Alabaster, Ala., said of how moderators had treated Trump during the first Republican debate this month. “Amen, Amen,” a woman nearby responded.

On paper, Trump should be a tough sell down South. He’s the GOP front-runner — but he’s also a loud, brash, thrice-married New Yorker with a reputation for both tough talk and softness on social issues. Rudolph W. Giuliani, who checked the same boxes and was the front-runner the summer before the 2008 primaries, barely made a ripple in the final results.

Some say Trump’s appeal in the region is different, and according to University of Mississippi journalism professor Curtis Wilkie, it has precedent. “There is a history of outrageous politicians who are able to develop a substantial following in the Deep South. There is a history of electing demagogues,” he said. “Trump’s support here is like it is in any other region: people who are angry, who are looking for some iconoclastic leadership or voice, and we have plenty of them.”

Voters interviewed in the region this month said they like Trump’s ability to speak bluntly with no apologies. They love his willingness to take on anyone or thing that gets in his way. But there were concerns too: worries about whether his brashness may backfire, and uneasiness with his comments about women.

Mary Weddington sat in a booth at a McDonald’s in Forrest City, Ark., last week, a crumpled wrapper from a sausage biscuit on the table in front of her. She said she is looking for a presidential candidate with Christian values. She said that on the basis of what she has seen in the past few weeks, it is clear that Trump is not that person. Weddington said she was upset when Trump said after the first Republican debate that Fox News Channel anchor Megyn Kelly had “blood coming out of her wherever.”

During a town hall meeting in New Hampshire, GOP presidential candidate Donald Trump slammed 2012 presidential nominee Mitt Romney, saying that he "choked." (Reuters)

“If he just said she had blood coming out of her eyes, and left it alone, it would be fine. That was wrong,” Weddington said. But he went too far, and she was offended.

“As a woman,” she said. “As a Christian. You just don’t do that.”

But despite the doubts, Trump’s foray here is creating more uncertainty in the newly competitive “SEC primary” states, named for the top-flight college athletic conference. The traditional Southern campaign prize — the early-voting state of South Carolina — is now just one target on a crowded map. Voters who have rarely received regular attention from candidates well before they head to the polls are not only being showered with unaccustomed attention from the GOP’s White House contenders, but they’re also getting that attention earlier and more often than ever before.

Alabama has been a surprisingly popular stop for candidates this month. Cruz — who blitzed the region this month on a seven-day, 20-stop “Cruz Country” road trip — has made two visits to the state this month, with another to come. Walker will headline the Alabama Republican Party’s summer luncheon Saturday, as he works to line up endorsements and support in the region. Retired neurosurgeon Ben Carson and Bush will stump in the state next week.

Trump’s choice of Mobile for his event Friday is notable, Wilkie said. The Gulf Coast boasts a substantial Catholic population, with a less-pronounced strain of Protestant fundamentalism. Trump, who is Presbyterian, has been criticized by some evangelical activists as sounding flippant when talking about his faith.

Roger Stone, a longtime Trump adviser who split with the campaign under disputed circumstances this month, said the real estate magnate’s target audience includes the military families that live on and around the numerous bases and facilities in the Florida Panhandle, and on the Gulf Coast of Mississippi and Alabama.

“It’s a place where the Bushes have traditionally had strength,” Stone said. “Trump is coming to them with a message that’s a perfect fit: pro-military patriot but someone who wants America to stop being humiliated abroad.” He said Trump’s pitch could intrigue voters including members of Kentucky Sen. Rand Paul’s anti-war bloc and those who are simply looking for a fresh face with outsider bona fides.

Trump’s connections to the South are not as long-standing and deep as those of candidates who hail from the region or have lived and campaigned there for decades — roughly half the Republican presidential field. But although Trump’s political arm has rarely extended there, Stone argued that his celebrity and personality make up for it. “He speaks the way they speak,” Stone said. “The goal for him is to get on a roll after the early states and then roll through the South.” No state is safe, he said: “Florida is another state there to watch. I wouldn’t assume it’s locked up for Rubio and Jeb.”

Others are skeptical of the benefits of this summer stumping south of the Mason-Dixon. Stuart Stevens, who was Mitt Romney’s chief strategist in 2012, dismissed the suggestion that August campaigning here, whether by Trump or others, would yield long-term political benefits. “Love the South, but the SEC primary will be decided very late and [be] heavily influenced by the earlier races,” he said. “Unless it’s fundraising, right now it seems a waste of time when the earlier races are key to survival.”

Retiree Bruce Agnew showed up for a morning biscuits-and-gravy event for Cruz in Chattanooga, Tenn., this month. But Cruz wasn’t the candidate on his mind.

“I’m for Donny boy,” Agnew said. He says he knows the mogul isn’t a perfect candidate, conceding that Trump has said some things that have disappointed him, particularly about women and immigrants. But at least for now, those missteps aren’t enough to persuade the 64-year-old to shift his support.

“I’m on his team so far, and I’ll ride him until either he wins or he alienates me,” Agnew said. “Is there any doubt he’s the most brash and brazen of all the candidates, Republican and Democrat? And quite frankly that is part of his appeal to me, and apparently to millions of others.”

Others are receptive but skeptical. Murray Gaston, 56, an engineer from Birmingham, Ala., has found himself conflicted about Trump. He appreciates the businessman’s tendency to speak his mind and stick his thumb in the eye of the establishment.

“I think it is healthy. I think it has engaged a number of people in the political process,” Gaston, who chose his words carefully, said of Trump’s run while standing in the parking lot of a Birmingham church after services on a stifling summer Sunday. “At the end of the day, it will have been a positive experience for the party.”

Despite this, Gaston won’t be supporting Trump in the primaries and thinks the candidate’s comments about Kelly went too far. They will mark “the beginning of the unraveling of his campaign,” he predicted. Candor “has to be delivered respectfully. He has failed to deliver respect with his candor,” Gaston said.

Whether Trump claims any Southern territory, he’s already captured the imagination of Southern voters such as Allan Brooks, 62, who attended Cruz’s event in Chattanooga. The retiree said he had not made up his mind about whom he plans to support, although a few, including Cruz, Sen. Marco Rubio (R-Fla.) and Paul, are high on his list. But none of them, he said, have grabbed the public’s attention, and his, as Trump has.

“He has struck a chord with the American people. He speaks the truth,” Brooks said. “It may not be the way people want to hear him speak, but he speaks the truth, and it is very refreshing.”

Robert Costa and Jenna Johnson contributed to this report.