As the Courier Journal reported:

Booker's participation in recent protests against police brutality and racism in his hometown of Louisville catapulted him into the national spotlight and led to a spike in interest and support for his candidacy among people within and outside of Kentucky.

The protests Booker joined have focused heavily on Breonna Taylor, a 26-year-old Black woman and emergency room technician who died after Louisville police officers shot her in her own home in March. Taylor's case brought a lot of attention to Louisville and, by extension, to Booker and the calls for justice he has made in solidarity with other protesters.

The coronavirus led to an emphasis on mail-in ballots and the abrupt closure of a number of polling places across the state. The closures, The Nation correspondent John Nichols noted, leave some questions about what could have been.

'A Very Strong Run,' But Booker Falls Short to Establishment-Backed McGrath in Kentucky Primary
"McGrath's campaign collapsed just a bit too late for Booker."