Sanders not surprised by Obama endorsing Clinton: White House

"The President has had the opportunity to speak to Senator Sanders now three times in the last week, and as a result of those conversations, I would think it is fair to say that Senator Sander was not at all surprised by today's announcement," White House Press Secretary Josh Earnest said yesterday.

Earlier in the day, Obama met Sanders at the White House, immediately after which he issued an email and a video announcing his decision to endorse Clinton, the former Secretary of State.

Sanders also vowed to foster party unity to take on Republican nominee Donald Trump.

Clinton, who reached enough delegate this Tuesday, is the first women presidential candidate of a major US party.

Earnest said the video was recorded Tuesday.

"Secretary Clinton's campaign has already announced that there will be an event, and the President is very much looking forward to travelling to Green Bay, Wisconsin, Title town, with Secretary Clinton to appear with her in person at a campaign event, and build support for her campaign in the state of Wisconsin -- a state that President Obama won twice," he said.

"I'm not going to get into the details of their interactions, but I assure you that Senator Sanders was not surprised," Earnest said in response to a question.

Earnest said that the Vermont Senator began his statement in the driveway in front of the White House today by saying that President Obama and Vice President Biden had made a commitment to him early in the process that they would not put their thumb on the scale.

"And Senator Sanders himself said how much he appreciated that President Obama and Vice President Biden kept that promise," he said in response to a question.

He said it is up to Sanders to decide how long he wants to continue to be in the race.