During a news conference, Kaine said he wasn't lobbying for the vice presidential slot, CNN reported.
"I haven't sought it, I'm not running for it, I'm not asking for it" Kaine said, "I never asked anything of the campaign. I didn't endorse him to get anything. I endorsed him to help him."
Earlier, sources close to Kaine reported he had "very serious" conversations with Obama, the presumptive Democratic Party nominee, and provided documents to the campaign for background checks, The Washington Post reported.
Kaine said one reason he backs Obama is because he believes the Illinois senator could win Virginia, The Hill said.
"Right now, Virginia is definitely in play," Kaine said. "And I'm going to be helpful there in whatever capacity."
Also reportedly being seriously vetted by campaign staff are Sens. Evan Bayh of Indiana and Joseph R. Biden Jr. of Delaware. Kaine and Kansas Gov. Kathleen Sebelius are the only state leaders thought to be seriously considered, sources close to Obama said.
Others reportedly being considered include Sens. Christopher J. Dodd of Connecticut and Hillary Clinton of New York, and former Sen. Sam Nunn of Georgia, the Post reported. Sens. Chuck Hagel, R-Neb., and Jack Reed, D-R.I., are thought to be long shots.