The phrase "uphill slog" refers to a difficult and tiring task or journey that requires a lot of effort and perseverance, just like climbing up a steep hill. Full definition
Along with having plenty of their own incumbents to defend, that's part of the reason Democrats have always had a steep uphill slog to take back the Speaker's gavel. (rollcall.com)
Again, it's testament to Namco's design that when playing the track backwards it did feel rather different — downhill sections became uphill slogs, and vice versa. (gamesasylum.com)
Waist high cover is central and capturing the big guns requires a slow uphill slog while enemy fire rains down. (dagersystem.com)