Des Moines, Iowa (CNN) Jeb Bush faces many challenges in his bid to become the Republican presidential nominee: a position on immigration that's unpopular among many primary voters, a last name that evokes strong feelings and an insurgent Donald Trump who shows no sign of giving up his commanding lead in the polls.

But perhaps the biggest challenge for the former Florida governor is himself.

After a flat performance in the first debate and a slide backward in national and early state polls, the former Florida governor has taken to calling himself the "joyful tortoise" of the race, a role that many did not expect the candidate with more than $100 million to be playing. But at a time when Republican voters are looking for a candidate to channel their anger and frustration, Bush's bookish -- sometimes awkward -- demeanor is preventing him from connecting with wide swaths of the primary electorate.

He refuses to compete with Trump's antics and swatted away questions about his current position in the race during his recent visit here.

'Long haul'

"This is a long haul man," he told a reporter as he dropped a corn kernel into his half-empty jar at the Iowa State fair's corn kernel poll. "Slow and steady progress."

Friends and aides describe Bush as thoughtful, tough, and exacting, qualities they say make him a great leader. But those traits don't always translate well to the demands of a campaign driven by social media hijinks or to the glad-handing that takes successful candidates across the finish line.

Photos: Jeb Bush's life Photos: Jeb Bush's life Former Florida Gov. Jeb Bush waves as he takes the stage as he formally announces he is joining the race for president with a speech June 15, 2015, at Miami Dade College in Miami. Hide Caption 1 of 21 Photos: Jeb Bush's life Former Florida governor Jeb Bush shakes hands with attendees after speaking at the 42nd annual Conservative Political Action Conference on February 27 in National Harbor, Maryland. Hide Caption 2 of 21 Photos: Jeb Bush's life Bush takes a selfie with a guest at a luncheon hosted by the Chicago Council on Global Affairs on February 18 in Chicago. Bush delivered his first major foreign policy speech at the event. Hide Caption 3 of 21 Photos: Jeb Bush's life Bush hands out items for Holiday Food Baskets to those in need outside the Little Havana offices of CAMACOL, the Latin American Chamber of Commerce on December 17 in Miami. Hide Caption 4 of 21 Photos: Jeb Bush's life Bush waves to the audience at the Tampa Bay Times Forum in Tampa, Florida, on August 30, 2012, on the final day of the Republican National Convention. Hide Caption 5 of 21 Photos: Jeb Bush's life Bush (left) and wife Columba Bush attend the 2012 Lincoln Center Institute Gala at Frederick P. Rose Hall, Jazz at Lincoln Center on March 7, 2012, in New York City. Hide Caption 6 of 21 Photos: Jeb Bush's life President Barack Obama (left) speaks about Bush (center) while visiting Miami Central Senior High School on March 4, 2011 in Miami, Florida. The visit focused on education. Hide Caption 7 of 21 Photos: Jeb Bush's life Bush (left) speaks with Brazilian President in charge Jose Alancar during a meeting at Planalto Palace in Brasilia, April 17, 2007. Bush was in Brazil to speak about sugar and ethanol business. Hide Caption 8 of 21 Photos: Jeb Bush's life Then-Texas Governor Rick Perry (center) testifies as Bush (right) and then-Arizona Governor Janet Napolitano (left) listen during a hearing before the House Committee on Homeland Security on Capitol Hill October 19, 2005. Hide Caption 9 of 21 Photos: Jeb Bush's life Bush gives a thumbs up signal from his car as he leaves a local polling station after casting his vote in Coral Gables, Florida, November 5, 2002. Hide Caption 10 of 21 Photos: Jeb Bush's life Bush walks out of the West Wing after meeting with his brother, then-President George W. Bush, at the White House January 9, 2002. Governor Bush participated in the signing ceremony of the Everglades Protection Agreement. Hide Caption 11 of 21 Photos: Jeb Bush's life Then-Mexican President Vincente Fox (left) and Bush hold a press conference September 7, 2001, in Miami. Fox visited Florida to attend the Americas Conference and deliver a speech to speak about issues such as immigration. Hide Caption 12 of 21 Photos: Jeb Bush's life Then-President George W. Bush (right) is greeted by Jeb Bush on March 21, 2001, at Orlando International Airport in Orlando, Florida. President Bush was in Orlando to attend the American College of Cardiology Annual Convention. Hide Caption 13 of 21 Photos: Jeb Bush's life Bush speaks during a press conference at the Carandolet Government Palace in Quito, January 18, 2006. Bush and a businessmen delegation were in a two-day visit to talk about a free trade agreement. Hide Caption 14 of 21 Photos: Jeb Bush's life Bush speaks to reporters after meeting with the Florida State Cabinet at the Florida State Capitol Building November 16, 2000, in Tallahassee, Florida. Hide Caption 15 of 21 Photos: Jeb Bush's life Then-President George W. Bush (left) and Jeb Bush (right), raise their arms onstage following a rally at the Florida State Fairgrounds, October 25, 2000, in Brandon, Florida. Hide Caption 16 of 21 Photos: Jeb Bush's life Jeb Bush (left) and then-President George W. Bush stand with their arms around each other's shoulders at a rally in Miami, Florida, September 22, 2000. Hide Caption 17 of 21 Photos: Jeb Bush's life Then-President George W. Bush (right) and Jeb Bush go through the line for strawberries during a stop at the Stawberry Festival March 12, 2000 in Plant City, Florida. Hide Caption 18 of 21 Photos: Jeb Bush's life The Bush family, (left to right) former U.S. President George W., former Florida Governor Jeb, former President George H.W. and his wife Barbara, watch play during the Foursomes matches September 25, 1999 at The Country Club in Brookline, Massachusetts the site of the 33rd Ryder Cup Matches. Hide Caption 19 of 21 Photos: Jeb Bush's life Former President George H.W. Bush (second left), his wife Barbara Bush (left), their son Jeb Bush (center), then-first lady Hillary Clinton (second right), and former then-President Bill Clinton (right) look up to see the U.S. Army Golden Knights parachute team November 6, 1997 at the conclusion of the dedication ceremony of the George Bush Library in College Station, Texas. Hide Caption 20 of 21 Photos: Jeb Bush's life Portrait of the Bush family in front of their Kennebunkport, Maine house August 24, 1986. Pictured, back row: Margaret holding daughter Marshall, Marvin Bush, Bill LeBlond. Pictured, front row: Neil Bush holding son Pierce, Sharon, George W. Bush holding daughter Barbara, Laura Bush holding daughter Jenna, Barbara Bush, George Bush, Sam LeBlond, Doro Bush Lebond, George P. (Jeb's son), Jeb Bush holding son Jebby, Columba Bush and Noelle Bush. Hide Caption 21 of 21

A day before Donald Trump breezed through his hour-long visit to the Iowa State Fair, waving quick hellos from inside his buffer of a dozen private security guards with the bearing of an imperial candidate, Bush clocked four hours of aggressive campaigning -- relishing the chance to engage with voters in policy discussions.

After meeting him, voters invariably used words like "warm," "direct," "genuine," and "earnest" to describe the former Florida governor. Few doubt his qualifications or readiness for the intellectual rigors of the Oval Office.

But they are rarely dazzled in the same way they are by rival candidates like Trump, or Florida Sen. Marco Rubio, or even by Bush's brother, George W. Bush, who could lock eyes and grip the shoulder of a voter for seconds on the rope line, and leave them with a sense of a deep, personal connection.

For all his tortoise analogies, there is a restless quality about the younger Bush -- a sense that he is always in a hurry to get to the next milepost, even at venues as laid back as the Iowa State Fair.

At 6'4 and feeling "a little taller," he said Friday, in his black cowboy boots with "Jeb" emblazoned on the side, he moved briskly across the fairgrounds when other candidates might have strolled.

Many fairgoers came up to express their admiration for Bush's father and his brother. At one point, Bush told a voter clutching his mother's book that he had sobbed when listening to one part of the narrative on tape. (His mother, he added, didn't believe him).

But he seemed most engaged when confronted by substantive questions. When a young woman asked for a selfie and his immigration proposal, he screeched to a halt to tell her about his "five point plan" -- ticking off each of the five elements on his fingers in depth.

Light banter

While wielding a spatula at the pork producer's tent where tenderloin was sizzling on the grill, he brushed off a chance for light banter when someone asked whether he or his brother was a better grill master. ("I don't know how he is on the grill," he replied).

But standing next to Iowa Gov. Terry Branstad in his red apron, he dove into a wonkish policy discussion about an Iowa challenge to the federal regulations for agricultural runoff and the water quality rules imposed by federal officials.

"That should be a state issue wherever possible," Bush said, sampling his own pork chop on a stick while keeping a careful eye on the tenderloins he was flipping.

He effortlessly listed the average annual inches of rainfall in Florida, the attributes of Florida's "fragile ecosystem," and cited several examples of how runoff issues vary among states like Florida, Mississippi and Iowa.

"This administration has gotten really hyperactive in expanding dramatically what the definition of federal waters are. To get a permit to put a culvert in for your field? Or to get a permit for a drainage ditch or a drainage pond?" he said with indignation.

"They impose their will top down," he added, promising to reverse the rules. "The 10th Amendment is just as important as all the other bill of rights and we've trampled over it."

He is not in a hurry to give answers to questions that he is still thinking about. He paused for a long while after a reporter asked him Thursday night in Iowa whether he would like his own helicopter.

"There's no good answer to that," he replied after a beat, before moving on.

He also does not pretend to enjoy the more tiresome aspects of campaigning like the enormous press scrum that formed around him as he passed through the fair. When a photographer accidentally backed into a man in a wheelchair, Bush came to a dead stop in the street and turned to an aide: "Have they no shame?" he asked.

Flashes of impatience also flicker across his face if he doesn't like a question from a reporter, a trait his advisers hope to keep check in during the upcoming series of presidential debates.

At the same time, while he is criticized as rusty after more than a decade away from the campaign trail, he also demonstrates a style that is careful and self-aware as a campaigner, which can be an asset over the long run.

After ordering a fried Snickers at the fair, he ate it in a fashion that showed he had put thought into avoiding embarrassing photos -- taking a bite from the middle, not the end, and quickly dusting the powdered sugar off his mouth with a napkin.

Making the sale

Voters seem to like Bush after meeting him, but time and again after his events here Thursday and Friday, he had moved on before making the sale.

"He seems smart and capable," said 69-year-old Jerry Litzel, who came to hear Bush at the Polk County Summer Sizzle Thursday night. "But he's soft-spoken. I think we need someone who can stand up for the United States." (Trump was among the candidates Litzel said he was considering).

Robert Davis, a hairdresser from Des Moines who buttonholed Bush in the state fair's "Bud Tent" to tell him he was going to be the next president, was blunt when the candidate walked away.

"He needs to get his ball rolling," Davis said of Bush. The hairdresser is considering the former Florida governor along with Trump, who he likes because "he says what we think, out loud."

"You have to bring people in. You have to make them respond to you -- that is what Trump is doing," Davis said. "Bush hasn't showed that yet."

That is a worry even for voters who say Bush is their top choice, like Iowan Barb Wine, a 64-year-old Amway Distributor who also met the former Florida governor in the beer tent Friday.

Moments after Bush had sipped "a cold one" at 10:40 a.m., Wine asked him point blank to explain how he was different from Trump.

Photos: A look at political families Photos: A look at political families Presumptive Republican nominee Donald Trump introduces his son Donald Trump Jr. as he addressed a crowd this April in Indianapolis. Trump Jr. has said that if his father becomes president, he's interested in being his secretary of the Interior. Hide Caption 1 of 30 Photos: A look at political families Photos: Political families – Former Secretary of State Hillary Clinton and former President Bill Clinton attend a State Department dinner in 2012. Hillary Clinton is the presumptive Democratic nominee for president. Hide Caption 2 of 30 Photos: A look at political families U.S. Rep. Joaquin Castro of Texas, left, and his twin brother then-San Antonio Mayor Julian Castro at the 2012 Democratic National Convention in Charlotte, North Carolina. Now secretary of the Department of Housing and Urban Development, Julian Castro is a contender to be the Democratic vice-president nominee. Hide Caption 3 of 30 Photos: A look at political families Political families – Beau Biden embraces his father, Vice President Joe Biden, at the 2008 Democratic National Convention.. Before his death in 2015, Beau served as Delware's attorney general. Hide Caption 4 of 30 Photos: A look at political families Photos: Political families – U.S. Rep. Debbie Dingell succeeded her husband, former U.S. Rep. John Dingell, D-Michigan, in the seat he held for 58 years until his retirement in 2015. Hide Caption 5 of 30 Photos: A look at political families Political families – Liz Cheney, daughter of former Vice President Dick Cheney, announced that she was running for Senate in Wyoming in 2014. Her bid set up an intra-GOP battle with U.S. Sen. Mike Enzi, a three-time incumbent. She dropped her Senate bid in January 2014. Hide Caption 6 of 30 Photos: A look at political families U.S. Rep. Sander Levin, D-Michigan, comes from a prominent family in that state's politics. His brother Carl Levin was the state's senior senator until his retirement in January 2015. And his uncle, Theodore Levin, was a federal judge. Hide Caption 7 of 30 Photos: A look at political families Photos: Political families – The night after John F. Kennedy won the 1960 presidential election this family portrait was made in Hyannis Port, Massachusetts. Sitting, from left, Eunice Shriver (on chair arm), Rose Kennedy, Joseph Kennedy, Jacqueline Kennedy, head turned away from camera, and Ted Kennedy. Back row, from left, Ethel Kennedy, Stephen Smith, Jean Smith, President John F. Kennedy, Robert F. Kennedy, Pat Lawford, Sargent Shriver, Joan Kennedy, and Peter Lawford. Hide Caption 8 of 30 Photos: A look at political families Photos: Political families – The late U.S. Sen. Prescott Bush, R-Connecticut, center, was the father of former President George H.W. Bush, left, and grandfather of former President George W. Bush, far left. Hide Caption 9 of 30 Photos: A look at political families Political families – The Bush family is a bona fide modern American political dynasty. Former President George W. Bush and former Florida Gov. Jeb Bush are the sons of former President George H.W. Bush. George P. Bush, Jeb's son, is a Texas land commissioner. George H.W. Bush is the son of Prescott Bush, a senator from Connecticut. Here, the former presidents and Jeb, right, pose for a photo at the christening of the aircraft carrier USS George H.W. Bush. Hide Caption 10 of 30 Photos: A look at political families Photos: Political families – George P. Bush speaks during the 2011 Republican Leadership Conference in New Orleans. The grandson of former President George H.W. Bush is a Texas land commissioner. Hide Caption 11 of 30 Photos: A look at political families Photos: Political families – Former President Jimmy Carter spends time with his grandson Jason, wife Rosalynn, and daughter Amy in 1976. Jason Carter was a Democratic member of the Georgia State Senate. Hide Caption 12 of 30 Photos: A look at political families Photos: Political families – John Adams was the second president of the United States. His son John Quincy Adams was the sixth President. Hide Caption 13 of 30 Photos: A look at political families Photos: Political families – John Quincy Adams is pictured. Hide Caption 14 of 30 Photos: A look at political families Photos: Political families – New Orleans Mayor Mitch Landrieu and his sister, then-U.S. Sen. Mary Landrieu, are interviewed during a special edition of "Meet The Press" in New Orleans in 2010. Hide Caption 15 of 30 Photos: A look at political families Photos: Political families – Former U.S. Sen. Sam Nunn, his wife Colleen, daughter Michelle, and his grandchildren walk the beach at Sea Island, Georgia, in 2007. Michelle Nunn was a Democratic candidate for Georgia's U.S. Senate seat in 2014. Hide Caption 16 of 30 Photos: A look at political families Photos: Political families – Sen. Mark Udall, D-Colorado, and his cousin Sen. Tom Udall, D-New Mexico, attend a weekly Senate policy luncheon in Washington in 2012. Hide Caption 17 of 30 Photos: A look at political families Photos: Political families – Former Arkansas attorney general, Sen. Mark Pryor, holds a news conference in Washington in 2006. Pryor is the son of former U.S. Sen. David Pryor, D-Arkansas. Hide Caption 18 of 30 Photos: A look at political families Photos: Political families – Former U.S. Sen. David Pryor. Hide Caption 19 of 30 Photos: A look at political families Political families – Father-and-son New York governors, Andrew, left, and Mario Cuomo appear at a rally in 2006. CNN anchor Chris Cuomo is another of Mario Cuomo's sons. Hide Caption 20 of 30 Photos: A look at political families Political families – U.S. House Minority Leader Nancy Pelosi, D-California, is the daughter of late Thomas D'Alesandro Jr., a Baltimore mayor and congressman. D'Alesandro, center, attends Pelosi's swearing-in in 1978. Hide Caption 21 of 30 Photos: A look at political families Political families – George W. Romney, with his son Mitt and his wife Lenore in 1962, announces his intention to run for governor of Michigan. The elder Romney went on to run for president in 1968, and his son Mitt served as governor of Massachusetts before winning the GOP nomination for president in 2012. Hide Caption 22 of 30 Photos: A look at political families Political families – The Kennedy clan experienced a two-year absence on Capitol Hill beginning in 2011 with the departure of U.S. Rep. Patrick Kennedy, D-Rhode Island, shown here with his father, U.S. Sen. Edward Kennedy, at President Barack Obama's inauguration in 2009. The hiatus ended when U.S. Rep. Joseph P. Kennedy III, D-Massachusetts, was sworn in 2013. He is the son of former U.S. Rep. Joe Kennedy and the grandson of the late U.S. Sen. Robert Kennedy. Hide Caption 23 of 30 Photos: A look at political families Political families – Then-Rep. Harold Ford, D-Tennessee, left, and his son, Harold Jr. shake hands with supporters in this 1996 photo. Harold Ford Sr. announced earlier that year that he was retiring from the seat he had held for 22 years and Harold Ford Jr. won the seat that fall. Hide Caption 24 of 30 Photos: A look at political families Political families – Democratic New York state Sen. Jose M. Serrano is the son of U.S. Rep. Jose E. Serrano. Hide Caption 25 of 30 Photos: A look at political families Political families – U.S. Sen. Lisa Murkowski, R-Alaska, is the daughter of Frank Murkowski, who also represented Alaska in the Senate and was later the state's governor. 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He replied that he was a consistent conservative with a proven record.

"I don't assume it's my way or the highway," Bush told her. "I've got deeply held views, but there's a big difference -- I think you can pretty well see it, just in demeanor. I want to broaden out our message to win a larger number of people."

"I respect him and clearly he's made great progress in his campaign, but clearly we're very different. Ultimately, people are going to look at it and notice."

But "he's called you kind of a milquetoast?" Wine pressed Bush, "How do you respond to that?"

"Yeah, well, I go campaign," Bush replied. "I'm going to do it hard, campaign all over -- and I'll turn people towards us.... At some point, you've got to be substantive about what you're going to do."

Charm on the trail

For all his seriousness, Bush is not without his moments of charm on the campaign trail.

As he headed out of the fair Friday, he caught a bag of caramel corn that Glenda Hockridge, tossed to him from inside her cotton candy truck.

He circled back and insisted on paying. She refused, stating it was from the "goodness of her heart." But he wouldn't take 'No' for an answer, slapping the dollar bills on the counter and kissing her hand before darting away.

Hockridge was still beaming an hour later. The North Dakota independent said she was deciding between Bush and Hillary Clinton, and described Bush as "down to earth" and "understanding" of hardworking people like her.

"If he goes around kissing people's hands, his wife is a very lucky woman," Hockridge said. Asked her age, she demurred: "As long as a man kisses my hand," she said, "I'm 29 and holding."