By John Whitesides
PHILADELPHIA (Reuters) - Democrat Bernie Sanders demanded the party chairwoman resign and questioned the vice presidential pick of Tim Kaine on Sunday, raising doubts about Hillary Clinton's chances for party unity on the eve of her presidential nominating convention.
Lingering bitterness from the heated primary campaign between Clinton and Sanders erupted after more than 19,000 leaked Democratic National Committee emails seemed to confirm Sanders' frequent charge that the DNC played favorites in the race.
"I'm not shocked but I'm disappointed," Sanders said on ABC's "This Week," repeating a demand he made earlier this year that DNC Chairwoman Debbie Wasserman Schultz step down from the post.
CNN reported Wasserman Schultz would not speak or preside at the convention, a blow to the leadership of a party keen on projecting steadiness in contrast to the volatility of Republican nominee Donald Trump.
The controversy overshadowed preparations in Philadelphia for the four-day coronation of Clinton as the Democratic nominee to face Trump in the Nov. 8 White House election. The convention will open on Monday.
The cache of more than 19,000 emails leaked on Friday by the WikiLeaks website revealed DNC officials explored ways to undermine Sanders' insurgent presidential campaign, including raising questions about whether Sanders, who is Jewish, was really an atheist.
The day after Kaine, a U.S. senator from Virginia, made his campaign trail debut as Clinton's potential running mate, Sanders also said he would have preferred she pick U.S. Senator Elizabeth Warren of Massachusetts, a favorite of the party's liberal wing, as her No. 2.
"I have known Tim Kaine for a number of years... Tim is a very, very smart guy. He is a very nice guy," Sanders, who has endorsed Clinton, said on NBC's "Meet the Press."
"He is more conservative than I am. Would I have preferred to see somebody like an Elizabeth Warren selected by Secretary Clinton? Yes, I would have," he said.
A RUSSIAN CONNNECTION?
The frustration from Sanders, a U.S. senator from Vermont, suggested the convention could be less serene than hoped by the Clinton camp, which wanted to offer a contrast with last week's chaotic Republican convention.
Liberal groups and Sanders supporters were dismayed by the pick of Kaine, who could appeal to independents and moderates but has never been aligned with party liberals.
But the flap over the Wikileaks documents posed a new threat to party unity. Brad Marshall, the DNC's chief financial officer, apologized on Facebook on Saturday for an email in which he discussed how some voters in upcoming nominating contests in Kentucky and West Virginia would reject an atheist.
No names were mentioned, but Sanders was the only Jewish candidate.
"He had skated on saying he has a Jewish heritage," Marshall wrote in a May 5 email to three top DNC officials. "I think I read he is an atheist. This could make several points difference with my peeps. My Southern Baptist peeps would draw a big difference between a Jew and an atheist."
Sanders said he had not received a personal apology.
Robby Mook, Clinton's campaign manager, raised questions about whether Russians may have had a hand in the hack attack, and were interested in helping Trump, who has offered praise for Russian President Vladimir Putin.
“What's disturbing to us is that experts are telling us that Russian state actors broke into the DNC, stole these emails and other experts are now saying that Russians are releasing these emails for the purpose of helping Donald Trump," he said on CNN's "State of the Union."
"I don’t think it is coincidental that these emails were released on the eve of our convention," he said.
Trump campaign manager Paul Manafort said the Clinton camp was trying to distract from its party discord ahead of the convention.
"Well, it's pure obfuscation on the part of the Clinton campaign," Manafort said on ABC. "What's in those emails show that it was a clearly rigged system, that Bernie Sanders - Sanders never had a chance.”
(Additional reporting by Sarah N. Lynch and Valerie Volcovici; Editing by Mary Milliken)