Kamala Harris will on Friday unveil parts of her economic programme, including new tax relief for families and homebuyers and a crackdown on price gouging, as she tries to persuade voters she can tackle a cost of living crisis that has dogged the Biden administration.

The Democratic presidential candidate will lay out the plans in a speech in North Carolina, a battleground state where her Republican rival Donald Trump delivered his own speech on economic policy earlier this week.

Trump and Harris are battling for votes with just over 80 days to go before November’s presidential election. The Republican candidate has railed against inflation while vowing to drive down fuel and housing costs and setting out his own protectionist economic agenda.

The most significant of Harris’s proposals include a $6,000 tax credit for families with newborn children, an expansion of an existing credit for families with older children to $3,600 per year, and up to $25,000 in downpayment support for first-time homebuyers.

Harris’s plan to make housing more affordable will also include a goal of building 3mn housing units in four years.

The vice-president will also try to ban so-called price gouging on food and groceries, designed to stop corporations from “unfairly” running up profits, and will propose giving the Federal Trade Commission and state attorneys-general the power to penalise companies that do not comply.

Harris and Trump have traded barbs in recent days over who would be better positioned to shepherd the US economy. Trump, a former real estate executive, on Thursday held a press conference at his New Jersey country club, flanked by groceries as he accused Harris of being a “radical California liberal who broke the economy, broke the border and broke the world, frankly”. On Friday, the Trump campaign said “comrade Kamala” had gone “full communist” by proposing to fix prices for consumer goods.

Harris, who replaced President Joe Biden as the Democratic candidate last month, has pulled ahead of Trump in some polls but is under pressure to come up with her own detailed economic plan. Biden struggled to convince Americans that he had a plan to quell inflation, which jumped to a multi-decade high in 2022 but has drifted lower since then.

Trump has long enjoyed an advantage in the eyes of voters when it comes to economic issues. But the most recent FT-Michigan Ross poll found voters were slightly more likely to say they trusted Harris over Trump to handle the economy, with 42 per cent trusting Harris and 41 per cent backing Trump.

The University of Michigan’s index of consumer sentiment, which came out on Friday, showed sentiment among Democrats had improved by 6 per cent after Harris replaced Biden at the top of the presidential ticket, and rose 3 per cent among independents. Sentiment fell among Republicans by 5 per cent over the same period.