McCain said that the Democrats' opposition to Lieberman stopped him from being selected for the post after the Trump Administration signaled that he was on the shortlist.
"My Democratic colleagues clearly did [kill Lieberman's chances]," McCain told reporters Wednesday, according to CNN. "This is their nominee for vice president of the United States. If anything would make you cynical about this town, that's it."
Lieberman was indeed the Democratic vice presidential nominee alongside Al Gore in 2000, but later became an independent in 2006 and eventually endorsed McCain, a close friend, in 2008 — which upset Democrats.
Sen. Ben Cardin (D-Md.) said Lieberman's partnership with Kasowitz, Benson, Torres & Friedman, the law firm Trump has worked with in the past and is expected to represent the president on matters related to the current Russia investigation, disqualified the former senator.
"It would be hard to see an associate of the law firm that just was hired by the president to defend him, or to represent his interests is a better way of saying it," Cardin told CNN. "So, yes, I think it disqualifies him."