Kamala Harris unveiled an economic blueprint Friday heavy on popular measures to cut costs for Americans, while attacking powerful companies for price gouging, as she fleshed out her election platform ahead of the Democratic National Convention.

The speech in North Carolina - a vital battleground state - was the first time Harris, who jumped into the race against Donald Trump less than a month ago, laid out a vision for combating the inflation which soured voters on her boss President Joe Biden.

Promising to champion an "opportunity economy," she said "building up the middle class will be a defining goal of my presidency."

In an effort to connect with voters angry at Biden, Harris recounted her modest background, noting that she'd worked in a McDonald's during university studies.

And she acknowledged that while "by any measure, our economy is the strongest in the world..., many Americans don't yet feel that progress in their daily lives."

Taking a leaf from Trump's populist playbook, she threw out the idea of hefty tax breaks for families with children, help in accessing government-subsidized health care, and support for first-time homebuyers.

This came on top of an announcement Thursday that the White House has negotiated reduced prices for retirees purchasing common medicines from major drug manufacturers.

Harris also called on Congress to pass a first federal ban on so-called "price-gouging" by food companies that unfairly increase prices.

With the convention starting in Chicago on Monday, the proposals were meant to flesh out a come-from-behind campaign that has seen Harris spark huge enthusiasm in the Democratic Party, but offer little detail on how she'd govern.

The vice president, vying to become the first woman president, hopes the headline-grabbing proposals will distance her from Biden's unpopular management of price surges that hit ordinary Americans in the wake of the Covid pandemic.

Trump and the Republicans are trying to tie Harris to 81-year-old Biden, who abruptly dropped his reelection bid on July 21 and endorsed his vice president.

"Kamala Harris has had three-and-a-half years in office and all she's done is break the economy. Kamala can't shake the stench of Bidenomics," the Trump campaign said.

The Trump campaign referred to an "inflation nightmare for American families" and claimed "Harris's vision is a Soviet-style communism."

In reality, inflation is on a steady downward trend, while the US economy has avoided a much-feared recession, with strong job growth and record stock markets. However, the lingering effects from the Covid-related upheaval continue to be felt for regular consumers, ranging from prices on some food items to high interest rates for home buyers.

What's not yet clear is how the generous Harris tax breaks would be paid for. The non-partisan Committee for a Responsible Federal Budget said that Harris's measures would cost more than $1.7 trillion over the next decade.

Billionaires vs middle class? 

Harris, 59, has mirrored some of Trump's populist strategy, including a proposal to end taxes on restaurant workers' tips.

At the same time, Harris is drawing a contrast with 78-year-old Trump's economic vision, painting him as being pro-millionaires and risking sharply increased costs for Americans through his proposal to slap tariffs of 10-20 percent on global imports.

"Donald Trump fights for billionaires and large corporations... I will fight to give money back to working and middle-class Americans," Harris said.

She said Trump's plan to impose across-the-board trade tariffs -- in line with his protectionist policies -- would result in importers passing prices to consumers.

"He wants to impose what is in effect a national sales tax," she said.

Much of Biden's economic agenda is transferring straight over to the Harris campaign.

This includes his promise to eradicate "junk fees" that lure customers in with a low price before adding extras and keeping the president's no-tax-hikes pledge for those making under $400,000.

Until recently, polls showed that voters strongly preferred Trump to Biden on the economy. However, Harris is already starting to nullify that advantage and a new University of Michigan poll even shows her ahead.