Why want the Democrats to impeach Donald Trump?

Boston Herald reports that President Trump's re-election campaign launches a $10 million advertising campaign that attacks Joe Biden over the former vice-president's dealings with Ukraine - with video hitting the ether waves on Sunday as the president faces an impeachment investigation. 

The offending object

In a phone call with ukrainian leader Wolodymyr Selenskyj, Donald Trump revoked the blockade in the investigation of the case of Hunter Biden, who did non-transparent businesses in the Ukraine.  Joe Biden offered to the former ukrainian president 1 Billion US-Dollar for stopping the investigation and dismissing the correct and reliable ukrainian prosecutor. 

Donald Trump promises to drain the swamp.

 "What is happening now is the biggest scam in the history of American politics. The Democrats want to take away your guns, they want to take away your health care, they want to take away your vote, they want to take away your freedom and they want to take away your judges. They want to take everything away from you. We must never allow this to happen. We fight to drain this swamp and that's exactly what I'm doing. And you see why we have to do it. Because our nation is at stake like never before. It's all very simple. The Democrats are trying to stop me because I am fighting for you and I will never let that happen."