President Obama Calls Clinton to Congratulate Her on Primary Wins "Her historic campaign inspired millions," the White House statement said,

 -- President Obama called Hillary Clinton on Tuesday night to congratulate the presumptive Democratic presidential nominee on her primary wins, according to the White House.

"The President congratulated Secretary Clinton for securing the delegates necessary to clinch the Democratic Nomination for President," the White House said in a statement released late Tuesday. "Her historic campaign inspired millions and is an extension of her lifelong fight for middle-class families and children."

Earlier in the evening, in an exclusive interview with ABC News’ David Muir, the presumptive Democratic nominee said she and the president were supposed to talk ahead of her remarks to supporters in Brooklyn on the historic primary night, but that "we haven’t yet connected."

"We were supposed to talk tonight but we haven't yet connected," Clinton told Muir at the Brooklyn Navy Yard, not far from Clinton’s campaign headquarters.

"We'll probably do it later tonight," she added.

Clinton said she and the President have "continually talked" throughout the primary season.

President Obama is poised to endorse Clinton and assume a more active role in the 2016 campaign -- a move which could come as soon as this week, the White House has signaled.

"I think he has signaled that he’s ready to fight the fight against Donald Trump and he's ready to fight the fight for the progress that we have made under his presidency," the former secretary of state said tonight about a possible endorsement, "Since I happen to agree that we have to maintain that progress, I think we’re going to be fighting side by side."

Obama told Democratic donors at a fundraiser in Miami on Friday: "We have to take this election seriously. Because we live in a fascinating media environment. Celebrity and fame is such a driver in this culture -- and everything's so contested."

As for his own role in the months ahead, Obama added that he’s brushing up on his stump skills.

"I'm out of practice," he said. "I haven't campaigned in a while."

For more of Muir’s exclusive interview with Clinton, tune into “Nightline” tonight and “Good Morning America” and “World News Tonight with David Muir” on Wednesday.