President Barack Obama is praising Hillary Clinton's selection of Sen. Tim Kaine as her running mate, saying in a Democratic Party fundraising email Saturday morning that Kaine is an "optimist," and like Clinton, "a progressive fighter.""He's the son of a teacher and an iron worker who's always got working families on his mind," Obama said in the fundraising email that went out under his own name on Saturday, reports Politico . "He spent nearly two decades and specialized in representing people who had been denied fair access to housing just because of what they looked like, or because they they had a disability."Saturday's email was sent by the Hillary Victory Fund, a joint fundraising committee between Clinton's campaign and the Democratic National Committee.Also, Obama wrote, "when a gunman killed 32 people on the campus of Virginia Tech, Tim knew he had a responsibility as governor to offer more than thoughts and prayers to the community he mourned with — and as a gun owner, he stood up to the gun lobby on their behalf."Kaine also made made Obama's vice presidential short list back in 2008 when the president was seeking his first term in office.Kaine had topped Clinton's list of potential running mates for some time before she announced her decision late Friday. She will formally introduce him to supporters during a rally at Florida International University in Miami on Saturday, just days before the Democratic National Convention opens in Philadelphia.Obama on Saturday further described Kaine as a "true progressive" and said the Virginia senator "will make a great vice president."