But she wasn't his first choice:
So only after nearly everyone else dropped did he settle for Clinton.
"He had, in fact, already made financial contributions to Clinton and two other candidates: Delaware Sen. Joe Biden, a longtime friend and political ally, and New Mexico Gov. Bill Richardson, a colleague in the National Governors' Association.
"Once the field was cleared," Rendell said, referring to the withdrawals of Biden and Richardson earlier this month, "I told them [the Clinton campaign] they could have my endorsement any time they wanted it."
This is an important endorsement for Hillary. Rendell was a popular mayor of Philadelphia, and now a popular Governor of Pennsylvania. People in and out of political circles care about what he thinks.
Obama better step it up.