President Joe Biden has been celebrating Labor Day in Pittsburgh on-and-off for more than a decade, twice using the city’s parade as a testing ground while he contemplated a presidential run.

When he returns to the city Monday, others’ races will be front and center, including Pennsylvania’s increasingly nasty Senate contest. Yet Biden’s own political strength will be put to the test as he embarks upon his most intensive in-person politicking since before the Covid-19 pandemic.

In Wisconsin and Pennsylvania on Monday, Biden heralded his economic record while celebrating “the dignity of American workers” at events with organized labor.

But he also hit