What is the downside to ramming through a new Justice before the new Senate is sworn in? The Dems impeached Trump, let lose mobs to destroy the country, vilified the GOP and about half of the population and promised to do something just like packing the court if they got power. Trump and Mitch must do everything possible to get a conservative into RBG's seat before the end of the year (they have until the new Senate is sworn in next year as far as I can tell). We already have riots and lawlessness in Congress. Now, we can get something in exchange for what they've put the country through.
If I was in a position to do so, this would be my recommendation to the President. If and when he is re-elected I would recommend he immediately propose increasing the Supreme Court to 12 or 15 justices and appoint tnem before his term in office is over. Remind the democrats it was their idea.
We do not want Roberts selecting the President in case it comes to that.
