On Wednesday, House impeachment managers began trying to convince their Senate colleagues to remove the president from office.

"President Trump withheld hundreds of millions of dollars in military aid to a strategic partner at war with Russia to secure foreign help for his re-election. In other words, to cheat," said Democratic Representative Adam Schiff, the House Impeachment Manager.

Over the course of nine hours, the team of seven Democrats laid out evidence and built a timeline of Trump's pressure campaign against Ukraine, with former Mayor Rudy Giuliani at the center of it.

"Giuliani continued to press Ukraine to do the President's political dirty work," said Representative Sylvia Garcia, another House Impeachment Manager.

Giuliani, the president's personal attorney, worked outside the regular diplomatic channels, even helping force out U.S. Ambassador Marie Yovanovitch.

"In order to complete his mission, Mr. Giuliani first needed Ambassador Yovanovitch out of the way. And so in early 2019, Mr. Giuliani launched a public smear campaign against the Ambassador," said Democratic Representative Jerry Nadler.

New York Congressman Hakeem Jeffries broke down the July 25th phone call where Trump pressed Ukraine's newly elected president to investigate the Bidens and a widely debunked theory that a DNC server hacked in 2016 is being held in Ukraine, an idea intelligence officials believe was pushed by Russia.

"The conspiracy theory that President Trump advanced on the July 25th phone call is stone-cold Russian propaganda," said Jeffries.

House Democrats continue their opening arguments Thursday and Friday; then it'll be Team Trump's turn. Earlier Tuesday, the President, speaking at the World Economic Forum in Switzerland, lashed out at Democrats.

"It's all a hoax. It's a con job. Like Schiff, he's a corrupt politician," President Trump said while at the conference.

But many of the facts of the case are not in dispute. The question is whether Trump's behavior warrants his removal from office.

"If this conduct is not impeachable, then nothing is," Schiff said.