John C. Calhoun at least. Going WAY back...
He had been Andrew Jackson’s VP, resigned, became one of the triumvirate (along with Clay and Webster) who fought against “King Jackson”. So, he went from being the ruling Democrat VP to being one of the three most powerful Senators, completely independent and critical of his home party. He even supported the Whigs a number of times, to get back at the Dems.
Anyways, good for Lieberman. Showing again that, although he is very liberal, he does ultimately care for the security of America and Israel. Despise his liberal beliefs, but I do respect him for the audacity of standing up to the national Democrats.
No, Calhoun never changed parties. He was more Democrat than Jackson. He served as secretary of state in the Whig administration from 1844-45, but Clay had declared Tyler no longer a Whig.