Amy Acton was elected governor of Ohio on Tuesday – a rare victory for the Democratic party in a state that Donald Trump carried three times.

Acton, 60, led Ohio’s health department through the first months of the Covid-19 pandemic. She will become the first woman to serve as Ohio’s governor. Her defeat of Vivek Ramaswamy, the biotech entrepreneur endorsed by Trump, also ends 16 years of Republican control of the governor’s office. She is the first Democrat to win the post since Ted Strickland in 2006.

Acton will lead a state that backed Trump by 11 points in 2024, and will govern alongside a Republican-controlled legislature, setting up potential clashes over tax reform, school funding and datacenters.

The contest to succeed Mike DeWine, the term-limited Republican, was often defined as “ugly”, with millions of dollars spent on attack ads. Ramaswamy won Trump’s endorsement the day he launched his campaign, and promised voters he would revive the American Dream by making Ohio income-tax free in a decade, cutting energy bills, and restoring “law and order” to Ohio’s cities.

Acton meanwhile centered her campaign on lowering costs, promising an earned income tax credit, a child tax credit of up to $1,000, a public prescription drug platform and property tax relief aimed at seniors and middle-income homeowners. She cast herself as a pragmatist, who had served in a Republican administration under DeWine.

In the final weeks leading up to election day, the race had become one of the most expensive and bitter in the country. Ramaswamy’s campaign aired an ad that featured Acton’s estranged mother calling her a liar. Acton’s mother lost custody of her after her husband, Acton’s stepfather, was indicted for raping Acton when she was 12.

The spot drew backlash from politicians of both parties, who urged Ramaswamy to take it down and apologize. But Trump and JD Vance, the vice-president, backed Ramaswamy’s minute-long ad, which the campaign said it would spend $4m on airing. The ad was eventually discontinued last week.

The journey to election day was tumultuous for Acton, a first-time candidate who, like Ramaswamy, had never held elected office. Early polls showed her trailing by double digits, with roughly a quarter of voters saying they had never heard of her. For months, Democrats speculated that better-known figures, including former senator Sherrod Brown and former congressman Tim Ryan, might enter the race.

By mid-October, Ramaswamy and his allies had spent more than $100m on ads against Acton, roughly three times what her campaign spent, hammering her role in the state’s pandemic shutdowns. At an October rally in Youngstown, Trump called Acton “a radical left lunatic”.

But polling moved steadily in her direction through the fall, and a string of October polls showed her ahead until her eventual victory.