As Donald Trump prepares to make his economic pitch to the nation, economists have warned that key parts of his policy platform – including steep tariffs and sweeping tax cuts – would probably increase inflation and strain the US’s finances.

The Trump campaign will set out plans to “make America wealthy again” as Republicans gather in Milwaukee on Monday for the first day of the party’s convention.

While the former president has pledged to “quickly” lower prices if he defeats Joe Biden in November’s presidential election, experts believe his policies risk sending them higher.

A second Trump administration would “defeat inflation, tackle the cost-of-living crisis, improve fiscal sanity, restore price stability and quickly bring down prices”, according to the Republican National Committee’s official policy platform, released last week.

But economists raised concern that his plans for steep tariffs on overseas goods and sweeping tax cuts would do the opposite.

“If you follow through on the tax promises, this just isn’t going to add up,” said Owen Zidar, professor of economics and public affairs at Princeton University.

“There’s a difference between reducing prices and reducing inflation,” Michael R Strain, director of economic policy studies at American Enterprise Institute, a conservative thinktank. “I don’t think anything that he’s proposing would lead to outright reductions in pricing.”

Inflation surged to its highest level in a generation two years ago, prompting policymakers at the Federal Reserve to hike interest rates to a two-decade high in an effort to cool the world’s largest economy. The consumer price index has since fallen from its 9.1% peak to 3%, but millions of Americans are still grappling with the higher cost of living.

While Trump is trying to blame Biden for inflation, and position himself as the man to “destroy” it, a Wall Street Journal survey of economists – conducted this month and published last week – found most believe inflation, deficits and interest rates would be higher under Trump than Biden.

Tariffs will ‘hurt’

The Republican policy platform, said to have been personally edited by Trump, included a commitment to introduce “baseline” tariffs. Imported goods would face a levy of 10%, according to his campaign.

Such a plan would “hurt the economy”, said Bernard Yaros, lead US economist at Oxford Economics. “If we do get across-the-board tariffs, that’s going to add to inflation immediately,” he said.

The tariffs are part of an effort to build America into “the manufacturing superpower of the world”, according to the Republican platform. Trump made similar pledges, in a clear pitch to the country’s industrial heartlands, in 2016. The results during his first administration were suboptimal.

“It’s going to be quite hard to turn the US into a manufacturing superpower,” said Zidar, who observed that services – from healthcare and haircuts to holidays – rather than goods “are 85% of the economy, in terms of value-added”.

Tax cuts will cost ‘trillions’

Trump’s proposed tax package – extending the cuts introduced during his first term, axing taxes on tips for hospitality workers and pursuing unspecified “additional” cuts – has raised fears that the vast US budget deficit would balloon on his watch.

His tax plans “will cost trillions of dollars at a time when the budget deficit is growing, and the national debt is on an unsustainable trajectory”, said Strain.

There is an “inconsistency between the big tax cuts and the central goal of reducing inflation”, said Zidar. “If they follow through on what they say, it’s going to be expansionary. It’s going to expand economic activity, increase interest costs [on US government debt] and boost inflation.”

Promises of lower federal spending are “actually pretty misleading”, he added, “when you take into account the plans on the tax side, and what that’s going to do to the deficit, and interest costs”.

Trump’s inflation plan

Trump’s stated plan to lower inflation has five key pillars: ditch restrictions on domestic energy production, cut “wasteful” government spending, reduce regulations, crack down on immigration and “restore peace” worldwide.

How likely Trump is to achieve such goals is an open question. A White House that is more supportive of US oil and gas giants is not guaranteed to persuade them to significantly increase production, Yaros said. But even if all these goals are achieved, “I don’t see any of this really having an immediate impact on inflation.”

Republicans argue that imposing tighter border restrictions and conducting widespread deportations will help “reverse” policies under Biden that they claim have driven up housing, education and healthcare costs. But economists warn Trump’s stated plans for immigration risk worsening inflation.

“If he’s serious about deporting several million people in a relatively short period of time, that would lead to big spikes in wage rates in those sectors, and a lot of that would be passed on to consumers,” said Strain. “We should expect to see big spikes in the price of fresh produce, big spikes in the price of hotel rooms, big spikes in the price of restaurant meals.”