Doug Mills, The New York Times / President Donald Trump walks to the Oval Office at the White House on Tuesday.

It has long been said that a lie can travel halfway around the world while the truth is putting on its shoes.

The truism has never been truer than in this impeachment season of discontent.

Just consider how far apart the Democrats and Republicans are on truth and lies.

* Only Tuesday, in a House Rules Committee hearing to set the parameters for today's historic debate over whether Trump's conduct toward Ukraine violated his oath of office, Georgia Republican Rep. Doug Collins despaired about there being "no fact witnesses" to the impeachment crimes.

Fact: There have been at least 17 fact witnesses.

To examine this further, let's look at just one sliver of the impeachment case: Trump's call with Ukrainian President Volodymyr Zelenskyy.

The White House, meaning Trump himself, released a summary transcript of the call, and it clearly shows the President asking Zelenskyy "a favor, though." Trump later in the call specified two things. Investigate Joe Biden (Trump's strongest political opponent) and find a server that conspiracy theorists think would discredit the mountain of evidence that the Russians interfered with our 2016 presidential election.

Who was also on that call listening? The list includes Jennifer Williams, adviser for Europe and Russia and staffer of Vice President Mike Pence, as well as Alexander Vindman, top Ukraine expert — both of whom testified in the impeachment inquiry hearings that yes, Trump did ask for those favors, and no, it was neither proper nor in U.S. national security interest. It was, however, in Trump's personal political interest. Both of those witnesses are fact witnesses. They heard the conversation with their own ears, making it firsthand, not hearsay, evidence.

Who else was listening on that call? Also included were Secretary of State Mike Pompeo, and Robert Blair, senior adviser to Trump Chief of Staff Mick Mulvaney — who told a gaggle of news reporters on air that such "quid pro quos" happen all the time, so "get over it."

But Trump refused to allow Pompeo, Blair, Mulvaney and others to testify. In fact, he made clear he would refuse to clear any requested testimony. That would include ex-National Security Adviser John Bolton, Energy Secretary Rick Perry, Vice President Mike Pence or Trump personal attorney Rudy Giuliani. Further, Trump himself was invited to participate in the hearings and declined.

No fact witnesses? Hardly. And there could have been more, but Trump clearly feels there is more to hide.

* Then there was fact witness U.S. Ambassador to the European Union Gordon Sondland, who devastated a weeks-long GOP defense by testifying about his role setting up what he called a "quid pro quo."

Sondland's texts put him at the center of the Ukraine scandal. And in an interview on Ukrainian TV the day after Trump's not-so-perfect call with Zelenskyy, Sondland was asked why he was spending time in Kyiv, Ukraine's capital. He answered: "President Trump has not only honored me with the job of being the U.S. ambassador to the EU, but he's also given me other special assignments."

Sondland, a Trump appointee, then described "the three amigos" team that would replace other diplomats to Ukraine (whom Mulvaney had recently pushed out). The "amigos — Sondland himself, Perry and Ambassador Kurt Volker — were "tasked with sort of overseeing the Ukraine-U.S. relationship between our contacts at the highest levels of the U.S. government and now the highest levels of the Ukrainian government," Sondland told Ukrainian TV.

Months later in his congressional committee testimony, Sondland said: " ... [Trump attorney] Giuliani's requests were a quid pro quo for arranging a White House visit for President Zelenskyy. ... Mr. Giuliani demanded that Ukraine make a public statement announcing investigations of the 2016 election/DNC server and Burisma. Mr. Giuliani was expressing the desires of the president of the United States, and we knew that these investigations were important to the president. Everyone was in the loop. It was no secret."

Then there is fact witness David Holmes, a top aide in the U.S. embassy in Kyiv, Ukraine. He testified he became convinced by the end of August that Trump had frozen the nearly $400 million in security aid for Ukraine — a country trying to fight off Russia — because he was seeking to pressure the country to commit to an investigation of Biden.

Holmes also told of overhearing — with his own ears — a memorable conversation over the phone between Sondland and Trump. Holmes testified he could hear Trump, who was speaking loudly, asking Sondland whether Zelenskyy was "going to do the investigation." Sondland told Trump that Zelenskyy "loves your [-]ss," and would conduct the investigation and do "anything you ask him to."

Holmes said Sondland later told him that Trump cared only about "big stuff that benefits the president" like the "Biden investigation." Sondland did not dispute that account when he testified, but said he did not recall specifically mentioning Biden.

* Finally, Republicans lawmakers and Trump on Tuesday again complained that the impeachment effort has been "unfair."

Why, then, refuse to let have staff testify? Why then refuse to participate? Why then, Senate Majority Leader Mitch McConnell, would you refuse to subpoena all these other "fact" witnesses?

The answer is clear. Truth is not what these Republican leaders want to send traveling even halfway around a hearing room, let alone the country or the world.