DETROIT (REUTERS) - Democratic US presidential hopeful Elizabeth Warren proposed on Tuesday (June 4) spending $2 trillion (S$2.7 trillion) on a new "green manufacturing" program to address climate change that would invest in research and exporting American clean energy technology.

The manufacturing program is the first in a new series of "economic patriotism" proposals Warren is unveiling intended to create American jobs and help US industry.

"This is going to be a big plan for bold structural changes," Warren said at a campaign rally in Detroit, Michigan.

Warren told the crowd of about 500 at a centre that teaches manufacturing skills that her proposal would be paid for by cutting subsidies in the oil and gas industry. Additionally, by all companies paying more taxes, she said, singling out Amazon.com.

Among the more than 20 Democrats in the field hoping to challenge Republican President Donald Trump in November 2020, Warren has distinguished herself as the most prolific proposer of new policy positions.

Several candidates have offered climate-related policy proposals, including Washington Governor Jay Inslee, who has made it the singular focus of his campaign, and former Vice-President Joe Biden, who also announced his US$1.7 trillion climate plan on Tuesday.

Warren said she had not read Biden's proposal when asked by reporters after her campaign event.

The newest proposal from Warren, a US senator from Massachusetts, lays out how she would carry out some of the policy goals outlined in the Green New Deal, which has the backing of liberal members of her party.

Warren began touting the proposal in a campaign trip to Michigan, a Midwestern state with a large manufacturing sector that shocked political observers in 2016 when voters backed Trump and helped propel him to the White House.

"When we're talking about manufacturing, when we're talking about real expertise, we're talking about Detroit," Warren said.

The plan is likely to draw criticism from opponents who will argue the price tag is too high and that trying to quickly overhaul the US energy sector would have crippling economic effects.

But Warren also released an evaluation of her three-part proposal conducted by Moody's economist Mark Zandi, who argued the plan would help the economy on a large scale.

"There is no free lunch, and big businesses, oil and gas companies, and multinationals pay for the cost of this plan," Zandi wrote. "The economy benefits, although it would take more than a decade for this benefit to be fully realised."

The first part of Warren's plan calls for spending US$400 billion over 10 years on clean energy research and development.

Warren said she believes the United States could one day use no fossil fuels. "It's part of our technological bandwidth," she said in a brief news conference after the Detroit rally.

Next, Warren proposed increasing the amount the United States spends on "American-made clean, renewable, and emission-free energy products for federal, state, and local use, and for export."

She said the United States currently spends US$1.5 trillion on defence procurement, which she called "bloated", and argued that an equal amount should be spent on clean energy.

As part of this proposal, Warren would require companies that sell to the federal government pay their employees at least US$15 an hour, that employees receive 12 weeks paid family and medical leave and be able to form unions. Labour practices were included in Green New Deal proposals.

Finally, Warren called for creating a new federal office responsible for trying to get foreign countries to purchase US clean energy technology.

Likening it to programs that help foreign countries buy US-made weapons, Warren would allocate US$100 billion to assist countries buying US energy technologies.

While acknowledging ambitious goals that liberal advocates have supported to reduce greenhouse gas emissions to net-zero by 2050, Warren said it was important that other countries cut emissions as well.

"We need other countries to slash their emissions, and that means we need to supply the world with clean energy products (at low enough prices to displace dirty alternatives) to put us on the right path," Warren wrote on Medium.