U.S. Democratic presidential candidate Bernie Sanders walks from the West Wing of the White House to speak to reporters after his meeting with U.S. President Barack Obama in Washington, Jan. 27, 2016. Kevin Lamarque/Reuters

Vermont Sen. Bernie Sanders said he did not ask President Barack Obama for an endorsement when the two met in the Oval Office Wednesday, just days before the first voting in the 2016 presidential campaign begins next week. Instead, he told reporters they had a "productive and constructive" meeting where they talked about "a number of issues" including foreign policy, domestic concerns and "occasionally a little politics."

There was “no formal agenda” for the meeting, White House press secretary John Earnest said in a statement Tuesday night. Obama and Sanders first talked about meeting when the Democratic presidential candidate attended the Congressional Holiday Ball in December.

The meeting comes at an important moment for Sanders, as he gears up to battle former Secretary of State Hillary Clinton in the Iowa caucuses. The race between Sanders and Clinton has heated up in recent weeks, as the two Democratic candidates have been neck-and-neck in Iowa polls ahead of the first nominating contest.

Clinton has met with Obama several times over the last year, and just last month the two had a private lunch at the White House, which Earnest described as a “mostly social occasion” at the time. Obama administration officials did not know when the president had last met one-on-one with Sanders, the New York Times reported.

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Obama has not endorsed a candidate in the Democratic primary contest, but he has expressed positive feelings about Clinton, who served as secretary of state after losing the nomination to him in 2008. In an interview with Politico last weekend, Obama also made several comments that suggest he supports Clinton.

Sanders addressed the chatter about the Politico interview Wednesday, denying that the president was trying to turn the race in Clinton's favor. “I don't believe that at all,” he told reporters Wednesday. The Vermont senator emphasized that before Obama became president, he campaigned for Sanders in Vermont and added that he would not forget that. He acknowledged the two disagree on some issues such as taxes and the president's Trans-Pacific Partnership trade deal, but said this is the case with any politicians.

"I have stood by his side where he has taken on unprecedented Republican obstructionism," Sanders said.

In the Politico interview from last weekend, the president praised both Sanders and Clinton, but described the former secretary of state as “more experienced than any non-vice president has ever been who aspires to this office” and said she is a “good, smart, tough person who cares deeply about this country.”

Obama attributed some of the Vermont senator’s success to the idea that comparatively few Americans knew him before he entered the presidential race. He added that if Sanders continues to do well, he would expect the media to examine the candidate’s ideas more seriously.

“If Bernie won Iowa or won New Hampshire, then you guys are going to do your jobs and, you know, you're going to dig into his proposals and how much they cost and what does it mean, and, you know, how does his tax policy work and he's subjected, then, to a rigor that hasn't happened yet, but that Hillary is very well familiar with,” Obama said in the interview.

After his meeting with Obama on Wednesday, Sanders said he was getting "updated on some of the issues facing this country" and said he believes the president is trying to do the right thing when it comes to fighting terrorism.