No he wasn’t. For sure he had leftist views but not a “huge lefty”.He could care less about who was in office or any particular bill. He was pretty much about making music and getting high.
Yes, Cobain was a leftist and was vocal in his leftist views. He also openly supported leftist causes.
He was a vocal supporter of the homosexual and pro-choice movement. Nirvana played at a gay rights benefit supporting No-on-Nine in Oregon in 1992, in opposition to Ballot Measure Nine, a ballot measure, that if passed, would have prohibited schools in the state from acknowledging or positively accepting LGBT rights and welfare.
Cobain was involved in Rock for Choice from the campaign’s inception.