As a little girl, if Hillary Rodham forgot to screw the cap back on the toothpaste, her father would toss the tube out the bathroom window. She would scurry around in the snow-covered evergreen bushes outside their suburban Chicago home to find it and return inside to brush her teeth, reminded, once again, of one of Hugh E. Rodham’s many rules.

When she lagged behind in Miss Metzger’s fourth-grade math class, Rodham would wake his daughter at dawn to grill her on multiplication tables. When she brought home an A, he would sneer: "You must go to a pretty easy school."

Clinton has made the struggles of her mother, Dorothy Rodham, a central part of her 2016 campaign’s message, and has repeatedly described her mother’s life story to crowds around the country. But her father, whom Clinton rarely talks about publicly, exerted an equally powerful, if sometimes bruising, influence on the woman who wants to become the first female president.

The brusque son of an English immigrant and a coal miner’s daughter in Scranton, Penn., Hugh Rodham, for most of his life, harbored prejudices against blacks, Catholics and anyone else not like him. He hurled biting sarcasm at his wife and only daughter and spanked, at times excessively, his three children to keep them in line, according to interviews with friends and a review of documents, Clinton’s writings and former President Bill Clinton’s memoir.

"By all accounts he was kind of a tough customer," said Lissa Muscatine, a longtime friend and adviser to Hillary Clinton. "Hard working, believed in no free rides, believed you had to earn what you’re going to get, believed his kids could always do better."

Presidential candidates often turn to hard-knocks family stories to help them connect to voters, but for years, Hillary Clinton refrained from sharing a detailed portrait of her childhood. In her 2016 campaign, she has shown an increased willingness to talk about her mother, a warm and devoted parent who had been abandoned by her own parents and who worked as a housekeeper as a teenager before she met and married Hugh Rodham.

But Clinton refers in only oblique ways to her father.

At a house party in Iowa this month, a supporter gave Clinton garlic pills to help her fend off illness on the campaign trail. The unexpected gift brought about an olfactory, and impromptu, memory. "My late father was a huge believer in garlic," and not the odorless kind, Clinton said. "I couldn’t believe it when I saw him eating a garlic and peanut butter and jelly sandwich."

Even her Father’s Day message this year, posted on Twitter, was, essentially, an ode to her mother.

"I wish she could have seen the America we are going to build together," she wrote of Dorothy Rodham, who died in 2011. "An America," Clinton continued, "where a father can tell his daughter: Yes, you can be anything you want to be. Even President of the United States."

It is unclear what Hugh Rodham, an ardent conservative, would have thought about his only daughter’s trying (again) to capture the Democratic nomination.

He died of a stroke at age 82 in 1993, not long after he watched his daughter hold the Bible as his son-in-law was sworn into office, but long before she began her own political career.

When Bill Clinton eulogized Hugh Rodham, he described him as "tough and gruff" and said he "thought Democrats were one step short of Communism — but that I might be OK."

If Dorothy Rodham, a homemaker who never attended college but who raised her daughter to be confident and caring, is forming the emotional core of Hillary Clinton’s 2016 campaign, invoked as the inspiration behind her decades of public service, then Clinton’s father quietly represents the candidate’s combative, determined and scrappy side: the inspiration, friends said, that toughened his daughter up to not just withstand but embrace yet another political battle.

"He was such a force in the family, and there’s a lot of him in Hillary," said Lisa Caputo, a friend and former White House press aide who knew Hugh Rodham. "The discipline, the tenacity, the work ethic, a lot of that’s from him."

When Clinton does invoke her father on the campaign trail, she talks about him as a small-business owner who "just believed that you had to work hard to make your way and do whatever you had to do to be successful and provided a good living for our family." (Rodham shut his drapery business in 1965.)

Or, Clinton reminds people that her father was a Republican, an aside to show she can work with the other side. She did highlight her father’s geographic roots in her 2008 campaign, when she tried to win white working-class voters in the Democratic primaries against Barack Obama. Rodham was born to strict Methodists in working-class eastern Pennsylvania.

His father, Hugh Simpson Rodham, toiled in a Scranton lace mill, and his mother, Hannah Jones Rodham, came from a long line of coal miners. When she was a girl, Hillary and her two brothers spent summers at a cabin in the Pocono Mountains that had no indoor bath.

Clinton tries to visit her father’s grave, in the Rodham plot at the Washburn Street Cemetery in Scranton, when she passes through. She will return to Scranton on July 29 to raise money, her first trip back since she began her 2016 campaign.

"My grandfather, like so many of his generation, came to this country as a young child, as an immigrant, went to work at age 11 in the lace mills in Scranton," she says. "So when my dad was born in Scranton, he was born with that American dream."

But unlike her mother’s struggles, the darker parts of her father’s biography rarely come up when Clinton speaks.

Depression ran in the family. Clinton’s father found his brother Russell hanging but alive in the attic of his parents’ home and had to cut him down. Russell came to live with the Rodhams in their one-bedroom Lincoln Park apartment in Chicago. (In 1950, when Hillary was a toddler, the family moved to a two-story brick house in the affluent suburb of Park Ridge, Illinois. Russell rented an apartment nearby, but he died in 1962 when he left a cigarette burning, setting his home afire.)

Hugh Rodham, who was 230 pounds and 6-foot-2, with thick black hair and furrowed eyebrows, had played football at Pennsylvania State University and worked as a fitness instructor in the Navy during World War II.

He would hurl criticism at his wife around the kitchen table at 235 Wisner Street. When she encouraged Hillary to learn for learning’s sake, Hugh Rodham, who drove a Cadillac, would quip: "Learn for earning’s sake." If his children asked for an allowance for their many household chores, he would reply bluntly: "I feed you, don’t I?"

The family was isolated from its neighbors because of Rodham’s sour, demeaning nature and his misanthropic tendencies, said Carl Bernstein, who wrote a 2007 biography of Hillary Clinton, "A Woman in Charge."

"It was anything but ‘Father Knows Best,’" Bernstein said in an interview.

Dorothy Rodham was on blood thinners and unable to travel to see her daughter deliver the 1969 commencement speech at Wellesley. Hillary was devastated that her mother could not make it. Hugh Rodham attended instead.

Her relationship with her father had deteriorated as she drifted away from the party of Barry Goldwater and got swept up in the liberalism of the late 1960s.

"In typical Hugh Rodham fashion, he flew to Boston late the night before, stayed out by the airport, took the MTA to campus, attended graduation" and, after lunch with some of Hillary’s classmates, went right back to Chicago, Clinton wrote in her 2003 memoir, "Living History."

But their relationship was not without warmth.

Clinton and her father shared the same distinct laugh, a "big, rolling guffaw that can turn heads in a restaurant and send cats running from the room," as she described it in "Living History." They played heated games of pinochle (though Rodham was known to flip the table if he lost).

Rodham taught his only daughter that she could play sports and do anything the boys did. When she was racked with self-doubt at Wellesley and Yale, her father wrote her tough but tender letters telling her to buck up. "Even when he erupted at me, he admired my independence and accomplishments," she later wrote.

At his daughter’s wedding in 1975, Rodham was hesitant to give the bride away to Bill Clinton, a penniless Southern Baptist Democrat. "You can step back now, Mr. Rodham," the minister finally said.

In 1987, after Rodham had quadruple-bypass surgery, he and Dorothy moved to Little Rock, Ark., to be closer to their daughter and granddaughter, Chelsea. Hillary Clinton arranged for them to live in a condominium in the city’s leafy Hillcrest district.

Chelsea Clinton called her grandfather Pop Pop. The Rodhams attended her softball games, cheering her on and taking her and her friends out for frozen yogurt afterward.

"Her father at that point was beginning to decline, so I think it was to be close to family, and obviously Hillary was close to her family, especially to her mom," said Skip Rutherford, a longtime friend in Little Rock.

After Bill Clinton’s 1993 inauguration, when friends and family toasted the Clintons’ arrival in Washington at a party, Hugh Rodham was spotted stewing in a corner and nursing a drink. "My daughter is a real special girl," he told a friend from Scranton, Manny Gelb, who relayed the story to The Associated Press.

When her father had a stroke in 1993, Hillary Clinton, who was having difficulty adjusting to life in the White House, was deeply shaken.

After his life-support machines had been removed and Rodham lay in a coma at St. Vincent Infirmary in Little Rock, a scrum of news cameras and reporters waiting outside for any updates, Hillary Clinton traveled to Austin, Texas, to deliver a speech she felt obligated to give.

It became one of the more unusual addresses ever delivered by a first lady. Caputo, who accompanied Clinton on the trip, described the stream-of-consciousness speech — about the meaning of life, death and the need to remake civil society, delivered without a script — as "cathartic."

"When does life start? When does life end? Who makes those decisions? How do we dare to impinge upon these areas of such delicate, difficult questions?" Clinton asked the crowd.

She never mentioned her father, but quoted Lee Atwater, the Republican strategist who wrote that America was suffering from a "spiritual vacuum," caught up in its "ruthless ambitions and moral decay," before he died of cancer at age 40 in 1991.

"You can acquire all you want and still feel empty," Clinton said. "What power wouldn’t I trade for a little more time with my family?"

Hugh Rodham died the next day.