President Trump, in a Thursday tweet, hit Joe Biden over the fact former President Barack Obama didn’t endorse him until after the Democratic presidential primary was effectively over, a message the president sent hours after the Biden campaign released a 15-minute conversation between the likely Democratic presidential candidate and his former boss.

Vermont Sen. Bernie Sanders dropped out of the presidential race, clearing the way for Biden to become the Democrats’ presumptive nominee, on April 8. Obama waited until April 14 to endorse Biden, the day after Sanders formally endorsed Biden.

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“Obama, who wouldn’t even endorse Biden until everyone else was out of the primaries (and even then waited a long time!), is now making a commercial of support,” Trump said. “Remember, I wouldn’t even be here if it weren’t for them. I wouldn’t be President. They did a terrible job!”

Obama said multiple times before and during the Democratic presidential primaries that he wouldn’t endorse until there was a presumptive nominee.

But Obama’s absence from the campaign trail during the Democratic primary was notable because although it is not unusual for a former president to stay out of electoral politics and his own party’s primary especially, his former vice president was vying for the party’s presidential nomination. Former President Bill Clinton endorsed his vice president, Al Gore, in December 1999 while he was still engaged in a Democratic primary. Former President Ronald Reagan, on the other hand, waited until after the 1988 Republican presidential primary was essentially over to endorse his vice president, George H.W Bush.

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Obama and Biden, in the video, draw a contrast between how they handled national crises and how Trump is handling the coronavirus. They also touched on issues including health care and the racial strife that has spread across the nation in recent months.

“Can you imagine standing up when you were president and saying ‘it’s not my responsibility, I take no responsibility,” Biden asks Obama in the opening to the slickly-produced video.

“Those words didn’t come out of our mouths while we were in office,” Obama responded.

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The Biden campaign, for its part, appeared to welcome Trump’s comments on the video.

“”**checks comms plan for Biden/Obama video rollout**” Biden campaign National Press Secretary T.J. Ducklo tweeted. “Thursday, approx 12:30pm: Donald Trump tweets due to fear and insecurity at seeing two presidents discuss the nation’s challenges, prompting even more people to watch their conversation.”

Fox News’ Paul Steinhauser and Madeliene Rivera contributed to this report.