Nearly 20 years after President Bill Clinton declared that "the era of big government is over," Hillary Rodham Clinton is proposing muscular federal policies that would require hundreds of billions of dollars in new spending and markedly expand Washington’s influence in a host of areas, from universal prekindergarten to Alzheimer’s disease research.

Her presidential campaign has said little yet about the costs of her policy ideas or how she would pay for them, but Clinton is calling for government activism on a scale she has not sought since her failed health care initiative in 1993 and 1994. But if her liberalism was seen as out in front of where many Democrats were then, she now seems to be catching up to the mood of the party.

"It’s not that the philosophical fights in the party between the left and the center have been settled in favor of big government," presidential historian Robert Dallek said. "It’s that likely Democratic primary voters right now want to see government used to build the economy."

As ambitious as that may sound, Clinton’s agenda may not be enough to satisfy restive liberals, including those supporting Sen. Bernie Sanders of Vermont, who still suspect that she is not one of them. Nor is it likely to win many converts among the Republicans who control both houses of Congress and give her ideas (and Sanders’) little chance of gaining traction there.

The question is whether the lofty vision she is articulating as a candidate for the Democratic nomination is one that can be turned into a mandate if she is elected president.

"The problem for Hillary is that the country itself isn’t hungering for liberalism," said Jeremy Mayer, an associate professor of politics at George Mason University. "Republicans will be well-positioned to say to Hillary, ‘Great, and how are you going to pay for that?’"

Large majorities of Americans say in opinion polls that the federal government is too big or too powerful, creating a risk that Clinton’s proposals could overreach and turn off some voters.

Clinton is expected to begin spelling out details of her policies Monday in a speech about the economy. Meanwhile, her aides say she will seek to pay for them with higher taxes on wealthy Americans, along with cutbacks and closing loopholes elsewhere; the amounts in play are expected to be substantial.

Her most ambitious ideas, which her advisers say are designed to help families, include prekindergarten for all 4-year-olds, expanded access to child care, paid sick days and paid family leave, helping to make college students "as debt-free as possible," a higher minimum wage, company profit-sharing for employees, legal protections for people in the country illegally, and more financing for medical research.

Universal prekindergarten alone could cost tens of billions of dollars over the next decade, according to outside advisers to Clinton.

Against the sweep of Democratic Party history, Clinton’s proposals reflect a decided return to vibrant liberalism.

The government programs of Franklin D. Roosevelt — whose presidency Clinton regularly invokes — and Lyndon B. Johnson aimed to transform the lives of poor and elderly Americans with jobs, health care, and retirement benefits. But the consecutive electoral losses of Jimmy Carter, Walter F. Mondale, and Michael S. Dukakis in the 1980s — as well as President Ronald Reagan’s framing of government as "the problem" — gave rise to centrist Democrats like Bill Clinton who envisioned federal programs as safety nets rather than solutions to every social ill.

Government actions became more robust after the Great Recession, beginning in 2009 with President Barack Obama’s stimulus program, corporate bailouts and the Affordable Care Act. Hillary Clinton is moving to build on those programs.

Dallek said Democrats were increasingly determined to embrace Johnson’s view that, in the historian’s words, "What’s the point of being president if you’re not going to use the government and its powers to make progress in society?"

Friends and associates say Clinton is revealing her natural political self: a blend of progressive and pragmatic, an apostle of government policy as a force for change, and a more left-of-center leader than her husband.

"She’s an activist at heart and a liberal at heart, and she finally fits the times because more people want an expansive government than they did in the 1990s," said Al From, founder of the Democratic Leadership Council, a centrist group, now defunct, that had close ties to Bill Clinton. "The big challenge for her is, can she offer progressive policies that are constructive and efficient — but are ones that appeal to the liberal base but aren’t too hard-left?"

It is also a return to form by Hillary Clinton, who shifted in the 1990s to supporting more moderate and piecemeal policies after being vilified during the health care battle. She is on safer political ground now, not only because a growing number of Democrats identify as liberal but also because the economic challenges facing the country are more acute today than during her years in the Senate and as a presidential candidate in 2008.

Neera Tanden, president of the Center for American Progress and Clinton’s policy director in the 2008 campaign, said Clinton was offering a mix of ideas she has long supported, like prekindergarten and paid sick leave, and newer ones that address problems like income inequality and wage stagnation that have become worse since then.

"She talked about the family and economic issues in 2008, but there wasn’t a lot of traction," Tanden said. "The country has shifted a lot more. There is a lot more debate in the culture today about women’s roles and families and trying to make ends meet."

Gene Sperling, a former economic adviser to Bill Clinton and Obama, and someone whom Hillary Clinton has consulted in her current campaign, said that after more than three decades in public life and in her second national campaign, she has made clear that her goal is to have the biggest effect possible if she wins.

"I think the issues of economic inequality and middle class economic insecurity have become more serious and long-standing, and as a result are demanding bigger responses," Sperling said.

A sizeable portion of Democratic primary voters want even more dramatic changes than Clinton is calling for: The dismantling of banks and stricter regulation the financial industry, higher taxes on Wall Street firms and corporate profits, and reduced or even free college tuition.

Several Democrats in Iowa and New Hampshire, the first states to vote for the 2016 presidential nominees, said they remained skeptical that Clinton’s core beliefs were truly progressive, given her history as a pragmatist who, as a senator, sought common ground with Republicans and voted to authorize the 2003 invasion of Iraq.

"When Bernie Sanders talks about a political revolution, I believe it because that’s always been his message. But Hillary? Not so much," said Ellen Shipitalo, a graduate student in political studies at Queen’s University in Ontario, who attended a recent rally for Clinton in Des Moines, Iowa. "No Democrat I know really thinks she’ll change much as president."

Liberals may feel good about Sanders’ proposals — a breakup of big banks, $1 trillion for public works jobs, a "Medicare-for-all" system of universal health care — but many Democrats in Congress view them as impractical given Republican control.

Clinton’s allies said they believed her policies had a far better chance of success.

"If Hillary wins, and/or we take back the Senate, the mainstream conservatives who want to work with us will have the upper hand over their Tea Party members," said Sen. Chuck Schumer of New York. "If they lose three consecutive presidential elections, you’ll have Republicans who will say, ‘We can’t keep following the Tea Party.’"

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