Why is the midterm vote count taking so long in some US states?

Key races in Arizona, Nevada and Georgia - which could decide the makeup of Congress - are still undecided. Here's why

Two days after the US midterm elections, a sense of deja vu is descending over the country. In a replay of the excruciating events in 2020, when Joe Biden's presidential victory was declared four days after the polls closed, Americans are yet again asking themselves why they have to wait so long for election results.

Later in the week, it remained elusive which main party will control both chambers of Congress. In the Senate, Republicans hold 49 seats and the Democrats 48, with two states - Arizona and Nevada - not yet called, and Georgia headed to a runoff.