If Kavanaugh is put on the court and the Dems win the house they can thouroughly investigate him. If it becomes obvious he perjured himself the house can impeach him. But the senate can refuse to convict
him if it so chooses. Can he then be tried for perjury and if convicted be sent to jail?
If the Democrats win the House and immediately begin Impeachment Hearings against Trump and Hearings against Kavanaugh they will come across as bitter, vengeful, rabidly partisan out for revenge after taking control rather than interested in getting to work for the American people / this country.
They have been doing nothing but attempting to reverse the results of the 2016 election, results they still refuse to accept, since Trump won.