ABC News' Kate Snow and Sarah Amos Report: For those reading the tea leaves, there are strong signs the Clinton campaign may be preparing for the end.
Late last night an email went out to advance staffers-- the folks who usually prepare sites for future Clinton campaign events. The memo indicated that there was nothing on Sen. Hillary Clinton's schedule beyond a speech scheduled for the AIPAC conference on Wed morning in Washington.
The email told staffers this was not goodbye but there were no plans and therefore no locations where their services would be needed for now.
The campaign is giving those staff members, who are currently scattered from Puerto Rico to Montana and South Dakota, two options. They can use a plane ticket to fly to NY for a party on Tuesday night where Clinton will address supporters. Then, the email told them, they would be responsible for flying themselves home. Or they can use the ticket to fly to their home base to await further instruction.
When/if something is planned, they will get a call, the memo said.
Campaigning in South Dakota, former president Bill Clinton admitted Monday could be the last time he has such an active role in presidential politics.
"I want to say also that this may be the last day I'm ever involved in a campaign of this kind. I thought I was out of politics, 'til Hillary decided to run. But it has been, one of the greatest honors of my life to go around and campaign for her for president," said Clinton as he began his speech.
Watch the VIDEO HERE.
It was certainly not a long thought - nor something he seemed to want to dwell on. But for a man who has rarely shown even an inkling of defeat in the past year, even uttering the words said a lot.
Sen. Clinton will be based in Chappaqua Tuesday huddling with family and senior staff. The event Tuesday night at Baruch College is the first time Clinton has spent a primary night in a state that is not voting or about to vote.
But even as Clinton's campaign showed signs of slowing down, a Clinton campaign spokesperson came to the back of the press plane Monday afternoon as Clinton flew from Rapid City to Sioux Falls, South Dakota.
When asked about Clinton's definition of when a nominee would be determined -– because she has refused to accept the new 2,118 delegates number that the Democratic Party says is needed to clinch the nomination, spokesman Mo Elleithee said, "I think its pretty clear that she is not conceding," he said.
"I think its pretty clear that she is staying in this race. She is going, in the coming days, to be aggressively courting uncommitted superdelegates aggressively courting unpledged delegates, making the case to them that she is a candidate best ready to take on John McCain."
When asked directly when Clinton will step aside, Elleithee told reporters, "as she has said dozens and dozens of times she is in this race until we have a nominee...Until there is a nominee she is going to try to win support."
He continued, "until there is a nominee we are going to still work to become that nominee."