I'm not going to link to a lot of online articles about Trump and the Ukraine and the impeachment inquiry because you don't need me to find such pieces on the web. You might have trouble finding a webpage that doesn't have any.
But in your travels, I hope you'll read Ezra Klein, who to me gets to the point of this whole mess. Money quote: "That Trump would attempt such brazen collusion after the Mueller investigation shows the lesson he took from that experience is that he is unchecked and unaccountable. And perhaps he is right. After all, he has Senate Majority Leader Mitch McConnell to protect him."