Imagine a nightmare scenario:
The Democratic Presidential nominee wins California by an additional one million votes, and gains 800,000 votes in Texas, and wins extra popular votes elsewhere, winning the national popular vote by 6 million, but not gaining Texas in the Electoral College.
The Democratic Presidential nominee wins Michigan and Pennsylvania from Donald Trump, winning 36 electoral votes.
But Donald Trump has a chance to win New Mexico (5), Nevada (6) and New Hampshire (4) in the Electoral College. But let’s assume Trump does NOT win these states.
Donald Trump wins Ohio, Iowa, Wisconsin, Arizona, North Carolina and Florida by small margins, winning 89 electoral votes.
Donald Trump wins the Electoral College 270-268!
So, in summary, the only change under this scenario is that Trump loses Michigan and Pennsylvania, but wins every other state he won in 2016, and he wins by the barest margin!