The people who decide elections are largely suburban dwellers in the suburbs of Milwaukee, Philadelphia, Pittsburgh, Phoenix, Scottsdale, Las Vegas, and Atlanta. Those people are largely decently high-income earners, professionals, married with 1-2 kids, irreligious, and generally open to voting for a politician of either major party.
Right now, their concerns are that their budgets are stretched despite being high income-earners (because of inflation), that they feel nervous about visiting their awesome big cities on the weekend (because of crime), and that their kids education quality is suffering.
While those are their concerns, Republicans are giving time to Hunter Biden's corruption. That corruption is real, but it's not what the voters that matter care about. They tend to assume both parties are criminal enterprises.