MANCHESTER, N.H. (Reuters) - Democratic presidential candidate Elizabeth Warren on Thursday accused her more moderate rivals of failing to stand up to the rich and pledged to fix a “rigged” U.S. economy, as she sought to re-energize her stalled campaign.

Democratic 2020 U.S. presidential candidate and U.S. Senator Elizabeth Warren (D-MA) delivers a campaign economic speech at Saint Anselm College’s Institue of Politics in Manchester, New Hampshire, U.S., December 12, 2019. REUTERS/Brian Snyder

Warren delivered pointed criticisms aimed at several others vying to win the Democratic nomination to face President Donald Trump in the 2020 election, including former Vice President Joe Biden and Pete Buttigieg, the mayor of South Bend, Indiana.

In a speech to the New Hampshire Institute of Politics at Saint Anselm College in Manchester, New Hampshire, Warren also faulted unnamed Democrats for soft-pedaling their rhetoric for political reasons.

“Unlike some candidates for the Democratic nomination, I’m not betting my agenda on the naive hope that if Democrats adopt Republican critiques of progressive policies or make vague calls for unity that somehow the wealthy and well-connected will stand down,” she said.

The rebukes reflected a recent tactical shift for Warren, whose campaign spent much of the year largely refusing to engage in back-and-forth spats with her rivals.

The speech underscored an effort to return to a key theme that helped lift Warren’s campaign through the summer and early fall: The country’s political and economic systems are corrupted by money and special interests, ensuring the wealthy benefit at everyone else’s expense.

In recent months, Warren’s momentum has slowed in the face of sustained criticism from Buttigieg, Biden and others over her support for the sweeping healthcare restructuring known as Medicare for All.

There are 15 Democrats running for the party’s nomination to challenge Trump in November’s election. Democratic nominating contests begin in February and the campaign has become increasingly unsettled, with no clear front-runner.

“We will beat the most corrupt president in American history by campaigning on the most aggressive anti-corruption plan since Watergate,” Warren declared, referring to the scandal that led to former President Richard Nixon’s resignation in 1974.

A poll of Democratic voters in New Hampshire from radio station WBUR on Wednesday showed Warren, a U.S. senator from neighboring Massachusetts, had slipped to fourth place, behind Buttigieg, Biden and Sanders. New Hampshire holds the second state nominating vote in February, following the Iowa caucuses.

BETTING ON CHANGE

Warren on Thursday outlined three problems that have created what she said was a “rigged” economy: corporations’ pursuit of short-term profits at workers’ expense; many markets dominated by monopolistic companies; and working families who have seen their wages stagnate while costs balloon.

She ticked off one detailed policy plan after another - a hallmark of her campaign - that she said would reform the basic structure of the U.S. economy.

“My plans attack the root causes of our dysfunctional economy by rewriting the rules,” she said.

Warren laid out an argument for why her familiar call for “big, structural change” is a better approach than the more tempered rhetoric of some of her rivals.

“I know I will have to compromise, but that’s not where we start,” she said. “The choice for the Democratic Party in this primary is the same choice it faces in every primary: Will we bet on more of the same, or will we bet on change?”

Warren also accused other candidates of kowtowing to rich donors, saying they are “selling access to their time for money.” Warren has pledged not to hold big-ticket fundraisers during her campaign.

Without naming them, she faulted Biden for telling wealthy donors earlier this year that “nothing would fundamentally change” if he was elected and Buttigieg for offering special access to his “national investors circle” of top donors.

In recent weeks, Warren and Buttigieg traded barbs over the issue of transparency, prompting Warren to release details of her decades-old corporate legal work and Buttigieg to agree to allow reporters to attend his high-dollar fundraisers.

Buttigieg’s campaign fired back, accusing Warren of trying to shut out Democrats who dislike her approach.

“Senator Warren’s idea of how to defeat Donald Trump is to tell people who don’t support her that they are unwelcome in the fight and that those who disagree with her belong in the other party,” Lis Smith, a spokeswoman for Buttigieg’s campaign, said in a statement.

“We need to move beyond the politics and divisiveness that is tearing this country apart,” Smith said.

At a fundraiser in Palo Alto, California, on Thursday, Biden responded to Warren’s suggestion that his vision of working with Republicans was “naive.”

“A president is not allowed to say, ‘This is how I’m changing the tax structure, this is how I’m changing the environment,’” he said. “You need to actually get a consensus in the constitutional process.”