“This election is our last best chance to at least rein in some of the foolishness of this administration,” Obama told crowds in Ohio on Saturday, arguing that voters had an opportunity to challenge Trump’s policies and limit his political power.

The midterm elections will determine which party controls Congress for the remainder of Trump’s term, shaping the administration’s ability to advance its domestic and foreign policy agenda.

Campaigning in Ohio and Michigan, Obama acknowledged that economic concerns and inflation following the COVID-19 pandemic had contributed to Democratic losses in 2024, but argued that Trump’s policies had failed to ease the burden on American households.

“If you thought everything was too expensive before ‘you know who’,” he said, referring to Trump without naming him, “everything is more expensive now”.

Obama also criticized the administration’s handling of the war against Iran, arguing that the conflict had strengthened Tehran’s leverage over the Strait of Hormuz, a strategic waterway critical to global energy supplies.

The war has added to pressure on oil prices, leaving Trump facing questions over his economic promises as rising fuel costs weigh on consumers.

Trump acknowledged that oil prices were “temporarily high” but insisted that they would eventually decline.

“Our country is getting stronger and stronger all the time, and those pump prices are going to come down,” he said.

At a rally in Perry, Georgia, Trump defended his tariff policies, claiming they were generating substantial revenue, and repeated his pledge to provide every American adult with $5,000 if Republicans won control of both chambers of Congress.

“We’re taking in massive amounts of money through tariffs,” he said, while accusing Democrats of seeking to “loot your wealth” and “annihilate your borders”.

Trump also used derogatory language to criticize immigration from Libya, Yemen, Haiti and Somalia, describing those countries as “terror-infested”.

Addressing the war on Iran, Trump said he might pursue further military action or reach an agreement, without committing to either course.

“I’ve done it very effectively and I may have to finish it off, or maybe they’ll make a deal, but I’m not sure. Either way, we win,” he said.

Meanwhile, Obama mocked Trump’s White House renovations, saying: “What’s with all the gold? He’s got the White House looking like Saddam Hussein opened up a Cheesecake Factory.”

The former US president was campaigning for Democrat Sherrod Brown, who is challenging Republican Senator John Husted, and Democratic gubernatorial candidate Amy Acton, who is running against Republican Vivek Ramaswamy.

Obama also condemned a Ramaswamy campaign advertisement featuring Acton’s estranged mother calling her a liar. The advertisement did not mention that the woman’s husband had been charged with raping Acton when she was a child.

“In recent days, we’ve seen there is no line he will not cross. No low he will not sink to try to get in the limelight,” Obama said.

Acton accused Ramaswamy of exploiting her childhood to “save his struggling campaign”.

With early voting under way, the competing campaigns are increasingly focused on the US economic hardship, the consequences of the aggression on Iran, immigration and the political tactics shaping the contest for control of Congress.