Understood that a conviction in the Senate is a long shot but if Biden is guilty and democrats defend him from Justice, then the American public needs to see that.
If the shoe was on the other foot, democrats would be pounding this every day.
The Dems had no problem in impeaching Trump in December 2019 over Ukraine.
Pelosi announced an impeachment inquiry (no floor vote) on September 24, 2019.
10 Dec: House Democrats unveil two articles of impeachment against President Trump - abuse of power and the obstruction of Congress
18 Dec: The House votes in favor of both charges, impeaching the president and setting up a trial in the Senate in the New Year.
The articles were submitted to the Senate on January 16, 2020, initiating the trial. The trial saw no witnesses or documents being subpoenaed, as Republican senators rejected attempts to introduce subpoenas.
On February 5, Trump was acquitted on both counts by the Senate, as neither count received 67 votes to convict.