Battleground State
A battleground state can reasonably be won by either a Republican or Democratic candidate.
The constellation of these states has changed over time. For example, Florida was formerly considered a top presidential battleground state but is increasingly viewed as too challenging for a Democrat to win a statewide election.
In 2020, the top seven presidential battleground states that were won by the slimmest of margins were Georgia, Arizona, Wisconsin, Pennsylvania, Nevada, Michigan, and North Carolina.