Washington (CNN) Former President Barack Obama has not endorsed anyone in the Democratic presidential primary. But both former Vice President Joe Biden and former New York City Mayor Michael Bloomberg have featured praise from Obama in their campaign ads.

Vermont Sen. Bernie Sanders has now released an Obama ad of his own

Like Bloomberg, who dropped out of the race Wednesday after a poor showing on Super Tuesday, Sanders has a complicated relationship with Obama. Sanders has praised Obama and co-sponsored legislation with him, but he's also criticized Obama as insufficiently progressive, suggesting it would be a good idea if Obama faced a progressive primary challenger when he sought re-election in 2012. In 2013 Sanders said , "I'm not Obama's biggest fan."

Even if you ignore this history, Sanders' 30-second television spot, titled "Feel the Bern," omits some important context. Let's go through it line by line.

1) The first quote leaves out some words

The ad begins with Obama saying, in a voiceover, "Bernie is somebody who has the virtue of saying exactly what he believes. Great authenticity, great passion, and is fearless."

Obama did say those words, in a January 2016 interview with Politico. But he also said other words in the middle, which the ad omits.

In the full quote, Obama made clear that he doesn't know Sanders as well as Sanders' then-rival, Hillary Clinton.

According to the Politico transcript, the full quote is: "Bernie is somebody who -- although I don't know as well because he wasn't, obviously, in my administration -- has the virtue of saying exactly what he believes, and great authenticity, great passion, and is fearless."

2) Another quote is from 2006, not 2016

After an additional quote from the 2016 Politico interview, in which Obama noted that Sanders "got bills done" while serving on the Senate Veterans' Affairs Committee, the ad proceeds to Obama saying this: "I think people are ready for a call to action. They want honest leadership who cares about them. They want somebody who's gonna fight for them. And they will find it in Bernie."

The ad then cuts to a shot of Obama at the podium at the 2016 Democratic National Convention, where Obama says, "That's right. Feel the Bern!"

The concluding image of Obama at the podium might create the impression that he delivered this whole testimonial at the 2016 convention. In fact, Obama said the preceding lines in a speech in Vermont in 2006, when Obama was an Illinois senator supporting then-congressman Sanders' bid for the Senate.

3) The "Feel the Bern" quote came during an endorsement of Hillary Clinton

Obama did say , "That's right. Feel the Bern!" at the 2016 convention. But he said it while trying to get Sanders supporters to vote for Clinton, not while offering an endorsement of Sanders.

Obama was trying to unite the party behind Clinton after her contentious primary with Sanders. During Obama's lengthy testimonial to Clinton, he complimented Sanders supporters -- and promptly encouraged everybody to vote for Democrats.

"So if you agree that there's too much inequality in our economy and too much money in our politics, we all need to be as vocal and as organized and as persistent as Bernie Sanders supporters have been during this election," Obama said. There were cheers. Obama continued: "We all need to get out and vote for Democrats up and down the ticket, and then hold them accountable until they get the job done."

The crowd cheered again, and there was a chant of "Ber-nie!" Obama then said , "That's right -- feel the Bern!"

Obama's office declined to comment. Sanders' campaign did not immediately respond to a request for comment.