Mitch McConnell never had to stop Mitt Romney and Susan Collins from straying in order to enable Trump's complete victory. He just had to stop every other Republican senator from doing so, and he did.
Trump’s acquittal was never in question in the Republican-controlled Senate, but the uncertainty about whether to call witnesses — as had been done in each of the previous 15 impeachment trials — created last-minute drama amid new revelations about Trump’s move to strong-arm Ukraine into investigating his domestic political rivals.
In the end, McConnell held his conference together, arguing that witnesses would drag the trial out for weeks and delay other Senate work. Several Republicans acknowledged that the president did use nearly $400 million in military aid to Ukraine as leverage to benefit himself politically, calling it inappropriate, but argued it wasn’t grounds to oust him from office.
“What was, I think, the most persuasive was just the open-ended consequences of starting down that path, and particularly the delays inherent in litigation that would ensue in the middle of the trial,” said Sen. John Cornyn (R-Tex.).
McConnell was among the first to argue that Republicans should avoid calling witnesses despite Trump’s clamor for the whistleblower whose report triggered the House impeachment probe, former vice president Joe Biden and his son, Hunter, to testify. The leader warned in a mid-December lunch that a protracted witness fight would be dangerous for both parties.
“Mutually assured destruction,” he told them.
In he end, he told Trump to let him handle it and he did.
Meanwhile, McConnell was working to ensure Trump and the White House trusted him to handle the trial strategy as he dealt with a mercurial president who had his own ideas about the proceedings. In one phone call shortly before Christmas, McConnell bluntly told Trump that while the president was getting a lot of feedback about how the trial should be conducted, he knew the Senate better than anybody who had been advising the president and, most importantly, how to make his members comfortable.
McConnell told Trump that he needed to trust him, according to a person familiar with the conversations who spoke on the condition of anonymity to talk frankly. Trump responded that he did.
The administration mostly left the wavering senators alone — namely out of McConnell’s insistence. He warned Trump in the fall not to alienate moderates lest he make the situation worse, according to Republicans.
“The White House has not asked for calls,” said one senior GOP official close to the moderate senators. “They’ve not asked for meetings. They’ve not texted.”
As I've said before the Constitution was ready to handle Trump. It was not ready to handle a Senate majority leader as corrupt and as immoral as Mitch McConnell.