US Treasury Secretary Janet Yellen
US Treasury Secretary Janet Yellen argued the Biden administration is 'building the foundations' of America's future. AFP

US Treasury Secretary Janet Yellen on Thursday lauded the economic gains made under President Joe Biden, as the Democrat leader's reelection campaign revs up -- and his team seeks to show he has done more for the country than Donald Trump.

Yellen's comments come just days after Trump won the New Hampshire primary, making a 2024 rematch with Biden almost certain.

As the campaign moves into a new phase, Biden's top economic officials have been emphasizing the benefits of his agenda, including investments from the Bipartisan Infrastructure Law and Inflation Reduction Act.

"None of these policies are aiming to recreate an earlier era. This country and the world have changed and we cannot go back," Yellen told the Economic Club of Chicago, stopping short of mentioning Trump's trademark "Make America Great Again" slogan.

"What we need is a new future rooted in upgraded infrastructure and a modern tax system, fueled by 21st century industries, and with the middle class at its center," she said, claiming Biden's administration is "building the foundations of that future."

Yellen told reporters Wednesday ahead of her Chicago visit that Biden is "focused on tax fairness," discussing his agenda in a potential second term.

Looking ahead, he would seek to ensure tax cuts disappear for corporations, she said, speaking about parts of a Trump-era package due to expire next year.

"We're not negotiating new tax breaks for wealthy individuals," she added, noting that the president also plans to retain cuts for those making less than $400,000 a year.

Biden has struggled to win over Americans on his handling of the economy, but Yellen stressed in Chicago that authorities managed to defy recession predictions last year.

"At the same time, inflation has come down significantly," she said.

With rising wages, low unemployment and a robust labor market, Yellen argued that "middle-class Americans now have more purchasing power."

"Put simply, it's been the fairest recovery on record," she said.

She conceded however that "work is far from done," with prices of key goods still too high.

Answering questions after her speech, Yellen said she believes "inflation is coming well under control."

"People are getting ahead. They're seeing their fortunes improve," she added. "I believe that if inflation stays low, they'll begin to regain their confidence in the economy."

Biden's top economic advisor Lael Brainard, who heads the National Economic Council, also made a case on Monday for "place-based" policies in Biden's economic approach.

She laid out a strategy of investing in "left behind" communities and encouraging business involvement in neglected areas to revitalize the world's biggest economy.