Every impeachment poses two different set of questions for the House and Senate to consider. 1) There are constitutional questions: Are impeachment and conviction justified? 2) There are political questions: Are impeachment and conviction possible?
In 1868, Johnson’s impeachment grew out of a power struggle between the president and republicans, who held power in Congress. Johnson fought with Republicans over bills dealing with civil rights for freed slave, and terms for readmitting secessionist states. When the republicans passed the tenure of Office Act that barred the president from firing a member of his cabinet unless the Senate approved a successor, Johnson fired his Secretary of War Edwin Station, without getting Senate approval.
He was impeached by the republican congress, but he was able to strike a deal with moderate republicans. He sent word that since he doesn’t have a Vice President after Lincoln was assassinated the presidency would go to the Senate President Pro Tempore Benjamin Wade who was a radical republican and was unloved by moderate republicans. They struck a deal not to remove him from office.
Nixon decided to resign rather than face impeachment after Senate Republicans told him the the he had lost the support of the moderate republicans, and it looked almost certain the they would vote to remove him.
Clinton was impeached for lying about an affair he had with another consenting adult. After Kenneth Starr tried to connect him to the white water investigation and failed, it was the only thing that Starr was able to prove. After he was acquitted in the Senate, the president’s approval rating skyrocketed when they realized the Kenneth Starr was just out to get him for personal gain.
Out of all three presidents only one committed what would be considered a criminal act, Nixon. Another won was a political power struggle between two branches of government, and the third was treated as lying about an extra-marital affair that should have been within his family only. The one thing they have in common is that none of them involved foreign counties that have motives against the United States.
Trump guilt that was published showed him actually blackmailing a foreign government to dig up dirt on his political opponent, therefore trying to change the out in the 2020 election, and other things when added together proves by their own admission guilt by crimes and misdemeanors.
I’m not going into detail with each single one, I’m just providing you with the tools to read and find out yourself.