Advisers to Hillary Clinton, including former President Bill Clinton, believe that her campaign made serious miscalculations by forgoing early attacks on Sen. Bernie Sanders of Vermont and failing to undercut his archliberal message before it grew into a political movement that has now put him within striking distance of beating her in Iowa and New Hampshire.

According to Democrats close to the Clintons and involved with her campaign, Clinton and the former president are also unnerved by the possibility that Sanders will foment a large wave of first-time voters and liberals that will derail her in Iowa, not unlike Barack Obama’s success in 2008, which consigned Hillary Clinton to a third-place finish. They have asked her advisers about the strength of the campaign’s data modeling and turnout assumptions in Iowa, given that her 2008 campaign’s predictions were so inaccurate.

As the Democratic rivals prepare for what is likely to be a contentious televised debate Sunday night, the Clintons are particularly concerned that her “rational message,” in the words of an aide, is not a fit with a restless Democratic primary electorate. Allies and advisers of the Clintons say Sanders is clearly connecting with voters through his emotional, inspiring rallying cry that the American economic and political systems are rigged for the wealthy and powerful. By contrast, Hillary Clinton has laid out an ambitious policy agenda, but more recently has been stressing her electability and questioning the costs of Sanders’ ideas.

Most Clinton advisers and allies would speak only on the condition of anonymity to candidly assess her vulnerabilities and the Clintons’ outlook on the race. This article is based on interviews with 11 people — campaign advisers, outside allies, friends and donors — who have spoken to the Clintons about the race.

“Hillary is a pragmatic progressive — she’s not an advocate,” said Gov. Peter Shumlin of Vermont, who last week campaigned in Iowa for Clinton over his home-state senator Sanders. “She quietly pulls people together and gets things done. Even though that’s not in vogue right now, I think that’s what voters will want in the end.”

But Clinton’s problems are broader than just her message: Opinion polls show that some Democrats and other voters continue to question her trustworthiness and whether she cares about their problems. Recent polls show that her once-formidable lead over Sanders in Iowa has all but vanished, while he is holding on to a slight lead over her in New Hampshire.

Clinton and her team say they always anticipated the race would tighten, with campaign manager Robby Mook telling colleagues last spring that Sanders would be tough competition. Yet they were not prepared for Sanders to become so popular with young people and independents, especially women, whom Clinton views as a key part of her base. Given her many political advantages, like rich donors and widespread support from Democratic Party elites, she is also surprised that Sanders’ fundraising has rivaled hers and that her experience — along with her potential to make history as the first woman elected president — has not galvanized more voters.

“It was probably never going be a straight line — we hoped it would be but feared it wouldn’t be,” said James Carville, the Democratic strategist on Bill Clinton’s 1992 campaign and a longtime friend of the Clintons. “She’s performed solidly enough, but it’s been a hard race.”

Several Clinton advisers are also regretting that they did not push for more debates, where Hillary Clinton excels, to more skillfully marginalize Sanders over his Senate votes in support of the gun industry and the enormous costs and likely tax increases tied to his big-government agenda.

Instead Clinton, who entered the race as the prohibitive favorite, played it safe, opting for as few debates as possible, which were scheduled at times when viewership was likely to be low — like this Sunday at 9 p.m. on a long holiday weekend.

“In the debates, she has shined, and while conventional wisdom says they offer no upside to a front-runner, she would benefit from more,” said Carter Eskew, a Democratic strategist who was a senior adviser to Al Gore’s presidential campaign in 2000. (He is not a Clinton adviser.) “Her basic strength remains: She is strongest in comparison to others. Her seasoning and knowledge show best in contrast.”

Both Clinton and her husband believe she can still win the Feb. 1 caucuses in Iowa and the Feb. 9 primary in New Hampshire despite Sanders’ gaining ground recently and now being virtually tied with her in many polls in those states. But the Clintons also believe she can survive losses in both places because of the strength of her political organization and support in the Feb. 27 primary in South Carolina and in many March 1 Super Tuesday states and other big states to follow.

An uncommitted superdelegate, David McDonald of Washington, said that compared with eight years ago, Clinton was less prone to stumbling and had a better political operation in his state. But just like in 2008, when she faced an opponent, Obama, who could mesmerize crowds, Clinton risks being overtaken.

“Her voter base does not seem as gung-ho energetic as Sanders’ base,” McDonald said. “It may be that they feel like they are waiting for the real race to begin. But an enthusiastic base can make a big difference in the early stages of a presidential nomination campaign, and if Hillary can’t pull away from Sanders fairly early in the season, I suspect he will gain strength rapidly.”

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