Updated at 6:30 p.m. ET with more quotes from the White House briefing.

The White House did nothing to tamp down speculation Monday that Vice President Biden might mount a presidential bid in 2016. Press Secretary Josh Earnest heaped praise on the vice president and said President Obama could endorse — even in a race between Biden and his former Secretary of State Hillary Clinton.

"I wouldn't rule out the possibility of an endorsement in the Democratic primary," Earnest said at a press briefing. He also noted Obama would vote in the March Illinois Democratic primary.

To this point, Obama has been reticent to weigh in on the Democratic presidential primary, especially if it were to become a race between Clinton and Biden.

In February on NBC's Today show, for example, NBC's Savannah Guthrie asked the president in lightning-round-style questioning, "Hillary Clinton or Joe Biden?

"I love 'em both. Good try," Obama said, looking off camera, smirking.

Rumors have been swirling that Biden is seriously considering a bid for president, as questions continue to dog Clinton about her use of a personal email server as secretary of state.

The vice president has said he would make his decision by the end of summer. Summer technically doesn't end until Sept. 22. That timeline was backed up by Earnest on Monday.

Biden and Obama had lunch together Monday, and Earnest didn't dissuade reporters from thinking that the veep's presidential ambitions might be on the menu.

"I'm going to be cautious of not going down the path describing private conversations between the president of the United States and the vice president other than to tell you that those conversations tend to be wide-ranging and they cover everything from work to family," Earnest said. "I'll leave it to you to decide whether or not you think that this decision by the vice president falls in either of those two categories."

Earnest also noted that Obama has said that naming Biden vice president was the "smartest decision he'd ever made in politics."

Earnest reiterated, "It was, it was," after a reporter followed up assuming that naming Biden his vice-presidential pick was an even better one than naming Clinton secretary of state.

Earnest did note President Obama's "appreciation, respect and admiration" for the job Clinton did as secretary of state.

But, he said, "You could make the case that there is probably no one in American politics today who has a better understanding of exactly what is required to mount a successful national presidential campaign."

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