Just two years after winning his first run for political office, Ohio Sen. JD Vance is set to become vice president — ushering a new generation into power and offering a potential glimpse at the Republican Party’s future after President-elect Donald Trump’s second term ends.

JD Vance, a 40-year-old senator who transformed himself from a biting critic of Donald J. Trump to one of his fiercest defenders, was elected the next vice president of the United States on Wednesday, becoming the third youngest and among the least experienced and most polarizing politicians ever to hold the office.