Sanders campaign deletes tweet knocking Clinton

Washington (CNN)Bernie Sanders' campaign invoked Robert F. Kennedy in a Twitter comeback to Hillary Clinton on Tuesday.

For four minutes.
Then, the tweet was deleted. And the campaign hasn't responded to questions about why.
Clinton's campaign was live-tweeting the former secretary of state's speech on racism, piece-by-piece.
One of the @HillaryClinton account's tweets said: "Anyone asking for your vote has a responsibility to grapple with reality—to see things as they actually are, not just as we want them to be."
Here is the full context of Clinton's comments: "For many white Americans, it's tempting to believe that bigotry is largely behind us. That would leave us with a lot less work, wouldn't it? But more than half a century after Rosa Parks sat and Dr. King marched and John Lewis bled, race still plays a significant role in determining who gets ahead in America and who gets left behind. Now anyone -- anyone asking for your vote has a responsibility to grapple with this reality. To see things as they actually are, not just as we want them to be. I'd be the first to admit I don't have all the answers. I've made my own mistakes. I've walked my own journey. But I believe with all my heart we can and must do better."
The tweet, sans full context, sounded similar to the shots Clinton has taken at Sanders over the feasibility of his policy proposals.
The @BernieSanders account -- which is run by staff, not Sanders himself -- had a ready response, quoting Robert F. Kennedy. The tweet: "'Some people see things as they are and say why? I dream things that never were and say why not?' - RFK"
That tweet was deleted four minutes later, according to Politiwoops, the website that tracks politicians' deleted tweets. Sanders' aides have not responded to questions about why it was deleted.
This all comes as President Barack Obama leaves the door open to an endorsement in the Democratic presidential race.
During a news conference Tuesday, Obama said he's staying out of the Democratic contest for now, but "eventually I'm sure I'll have an opinion on that, based on my experience having been a candidate of hope and change and the cuts and bruises I have from seven years of trying to get things done."