As Clinton announces her campaign, it’s the data-obsessive Robby Mook who will run the show. And one of his tasks will be what to do with Bill

After months of hints and preliminaries, stumbles and awkward exchanges, Hillary Clinton will today take the wraps off her campaign for the presidency in 2016.

The roll-out will be deliberately underwhelming. No whoosh, razzmattazz or confetti, no helicopters or Clinton grandiosity. No expressions of entitlement. The substance of her Twitter announcement and short video message will not be that a Clinton is running for the White House again – no surprise to anyone – but to appeal to voters with a coherent message outlining why she wants the presidency and for what purpose.

Clinton gave a hint of that with a new epilogue to her memoir, Hard Choices, posted on the web on Friday, in which she said – referring to her granddaughter – that she was convinced that the future of America depends “on our ability to ensure a child born in the hills of Appalachia or the Rio Grande valley grows up with the same shot at success that Charlotte will”.

But will that, or the 18-month campaign to follow, be enough to reset voters’ opinions of Clinton, which have barely shifted over nearly 25 years of the Clintonland experience? It will be up to her clean-cut, 35-year-old political director, Robby Mook, to steer the candidate away from the campaign misadventure that doomed her 2008 effort to establish the Clintons as a dynastic political enterprise.

The Vermont-born Mook will be the first openly gay manager of a major presidential campaign. He takes the reins of the campaign with a track record as a low-key but formidable political operative.

Clinton advisers anticipate that he is close enough to the Clinton inner circle to be trusted, but experienced enough to challenge negative aspects of the Clinton package, from political self-entitlement to the blurred boundaries of the Bill, Hillary and Chelsea Clinton Foundation.

Mook’s appointment is of a different order to that of James Carville, the loudmouth who directed Bill Clinton’s first presidential bid. Selecting Mook, aides say, is indicative of Hillary Clinton’s desire for a low-drama operation.

Mook is rarely quoted in news stories; he has no Facebook page; and he has forgotten the password of his Twitter account. “He does not seek out the spotlight and in fact does everything he can to avoid it,” pollster Geoff Garin told the political magazine Mother Jones last week. Indeed, the manner of Clinton’s announcement today will be in sharp contrast to the lack of political sophistication expressed by her 2008 launch address when, coiffured and placed in a chintzy drawing room, she invited voters “to start a conversation” – an invitation that voters declined.

This time, Clinton aides say, the machine will be stripped of grandiosity and roll in a more humble fashion in an attempt to play up Clinton’s of-the-people attributes and show empathy with average American middle-class voters yet to benefit from the upturn in the economy over the past two years.

But with polls showing the Republican challenger Rand Paul ahead in Colorado and Iowa polls, Mook’s primary responsibility will be to fashion a modern political campaign from Clinton’s new Brooklyn headquarters.

In his track record, which includes working on Howard Dean’s 2004 campaign for the Democratic nomination, there is only one qualification that matters: running the successful Virginia governorship campaign for Clinton insider Terry McAuliffe last November.

McAuliffe’s first campaign for office had suffered many of the problems of Clinton’s 2008 effort. Both relied on old friends and advisers; both stumbled against better-organised, data-driven operations. And it was Mook who had run rare successful primary operations for Clinton in Nevada, Ohio and Indiana.

“Robby understands modern campaigns, the value of data and technology,” Obama adviser David Plouffe told Bloomberg in 2013. “He beat us three times; his footprint was on our back. He did the best job of anyone over there.”

According to the political legend that already surrounds McAuliffe’s improbable November victory, Mook is fastidious about campaign discipline and quashing infighting. “He wanted to make sure it was based on the most recent tactics and to make sure the campaign was strategic and data-focused,” said Michael Halle, who managed field operations.

Friends say Mook is a political nerd who lives and dies by data. During the McAuliffe campaign, recalls Halle, he was “absolutely anal about every meeting ending with action items”.

Last month ABC News published excerpts of Mook operation emails. The so-called “Mook Mafia” – Mook is a close friend of Marlon Marshall, who stepped down as a White House aide in January – spoke of wanting to “smite Republicans Mafia-style”. Mook added: “F U Republicans. Mafia till I die.”

Recent reports describe the difficulty that Mook faces corralling Clinton’s vast network of advisers, fixers, donors, lackeys, celebrity hangers-on and campaign veterans, as well as friends of the family triumvirate, into a coherent enterprise. “They just keep building on all of the people who are well intentioned, well meaning, extremely loyal. But all have an opinion and want to be heard,” one former aide and friend of Hillary, Patti Solis Doyle, told Mother Jones.

“The new boy on the block has to learn who those people are, how to accommodate them, and, importantly, how to harness them towards the common enterprise,” noted one Clinton insider.

One of Mook’s toughest roles may be muzzling Bill Clinton, whose outbursts in 2008 did little to help his wife’s campaign. The former president has already taken umbrage with the New York Times after it detailed ongoing efforts by his wife’s advisers to harness his “rare gifts and rash impulses”. While he will be included in strategic planning, his wife’s team will – according to the paper – likely assign him a senior aide in an effort to keep him on message.

Mook and the former president have a “great relationship”, says McAuliffe. “But Robby is happiest when he is in his office with his computers and his data.”

A large part of Mook’s job, then, will be to silence the kind of distractions that have characterised Clinton’s shadow second run for the presidency this year: more than a dozen trips that Bill Clinton took on convicted sex offender Jeffrey Epstein’s private jet, dubbed the “Lolita express”; how she erased emails on her home server which she used to conduct government business; or problems with foreign donations to the Clinton foundation – all while she served as secretary of state.

The son of a physics lecturer and a hospital administrator, Mook got his start in political campaign organisation as a 16-year-old on the phone banks for the Clinton-Gore 1996 campaign. After graduating from Columbia with a degree in classics six years later, he joined Dean’s insurgent presidential run. Still just 23, he is remembered as a workaholic. But the political neophyte learned on that campaign that you can’t compensate for a flawed candidate.

Word from within the Clinton camp suggests that Mook will get his way. He is said to have advised the candidate to speak out quickly and aggressively on the email issue, but Clinton took days to respond and, when she did, it was before a packed press conference, not a one-on-one sitdown with a campaign-selected interviewer.

Can Mook establish control over the Clintons? “It’s very difficult,” Patti Solis Doyle says. “I will tell you that.”

HILLARY CLINTON: FROM CHICAGO TO THE SENATE … AND BEYOND

1947 Hillary Diane Rodham born in Chicago.

1962 Hears Rev Martin Luther King speak at a church youth group.

1965 Attends Wellesley College, an all-female college near Boston, studying political science and psychology.

1970 Moves in with fellow Yale law student Bill Clinton.

1972 Works on Senator George McGovern’s presidential campaign.

1975 Hillary and Bill Clinton are married in Fayetteville, Arkansas.

1976 Joins the Rose law firm.

1978 Bill Clinton elected governor of Arkansas.

1980 Their daughter, Chelsea Victoria, is born.

1991 Bill Clinton announces he is running for presidency.

1992 Hillary defends her work for her husband’s presidential campaign: “I suppose I could have stayed home and baked cookies and had teas.”

1992 Bill Clinton elected president. Names his wife as chair of health care task force.

1998 Hillary stands by her man as Bill Clinton faces impeachment in the Monica Lewinsky affair.

2000 Elected to the Senate from New York.

2002 Votes “yes” on Senate Iraq war resolution.

2007 Launches her campaign for the Democratic nomination against Barack Obama and ends it the following year.

2009 Appointed secretary of state by President Obama.

2013 Testifies about attack on US Embassy in Benghazi.

2015 Announces second campaign for the White House.