Former Vice President Joe Biden’s expected to declare his candidacy for president on Thursday.

But when he does, don’t expect his running mate for two election cycles – former President Barack Obama – to speak out in support of Biden’s 2020 bid.

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The 44th president plans to remain on the sidelines right now in the race for the Democratic presidential nomination. Two sources familiar with Obama’s thinking say the former president has made clear he doesn’t plan on endorsing early in the primary process – if at all. They add that Obama prefers to let the candidates make their cases directly to the voters and that former first lady Michelle Obama feels the same way.

"He’s not likely to endorse in the primary," a source who talks with the former president told Fox News. "He believes that for the Democratic Party to move on, voters have to pick their next leaders. President Obama believes in the value of a competitive presidential primary."

While he’s remaining neutral, Obama has met over the past several months with a number of candidates in the large field of Democratic 2020 contenders – offering guidance from someone who’s gone through what they’re going through now.

"President Obama wants to help Democrats win and that is why he has been happy to speak privately with candidates seeking his guidance on the best way to lead the country," said Eric Schultz, a senior adviser to the former president.

The backing of the former president – who remains extremely popular with Democrats – would be highly coveted by the White House hopefuls.

Asked if Obama and Biden have met or talked in recent days or weeks, a source close to the former president would only say that the two men remain good friends and have stayed in close touch since leaving the White House.

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Biden has described himself in recent weeks as an “Obama-Biden Democrat, and I’m proud of it.”

While Biden will highlight his eight years as vice president under Obama, he isn’t the only contender in the field who served in the former president’s administration.

Former San Antonio Mayor Julian Castro, who launched his campaign in January, served as Health and Human Services secretary in Obama’s second term.

Obama's comment in January that "new blood" was needed in politics raised eyebrows, considering that Biden is 76 years old.