In 2016 the voters chose Trump knowing full well that he would most likely have to chose a replacement for the aging decrepit Ginsburg. Trump is the president and one of his duties is to name a replacement. You can bet that if 0bama named a replace and the senate was controlled by the dems they would have approved the nominee even if it was on January 19 2017.
Advice & consent as it pertained to judicial nominations - including for the USSC - was one of the key issues in that election, as it was in 2016.