Other than Bush in 2004, no Republican, not McCain, Romney, or Trump, has won a majority of the popular vote in this century. It is possible that the one party Democratic states of New York and California inflate the popular vote totals even though the Democrats will win. However, the demographic reality exists. If a moderate Republican like Nikki Haley or Mike Pence wins the GOP nomination, they may pick up suburban moderates but lose much of the MAGA vote. The conservative base is way more alienated than they were in the last two decades. If Trump wins the nomination, it will be difficult for him to expand his base. The only chance I see is if what remains of the white blue collar Democratic vote and minority voters disaffected with the upper middle class leadership of the Democrats defect in significant numbers.
Popular vote means diddly squat.