PHILADELPHIA — President Barack Obama is expected to deliver a speech Wednesday night that will defend his legacy while looking to extend it — in a way.

Obama, addressing the third night of the Democratic National Convention, will try to make a strong case for electing Hillary Clinton and rejecting Republican Donald Trump. He is expected to tout the Affordable Care Act (known as “Obamacare”) and the economic return of Midwestern automobile plants, present Clinton as a trusted partner in key decisions and knock Trump as lacking the judgment to hold the office, analysts said.

According to excerpts of his speech made available to the media, Obama will seek to draw a distinction between Trump’s and Clinton’s experience.

“Until you’ve sat at that desk, you don’t know what it’s like to manage a global crisis or send young people to war. But Hillary’s been in the room; she’s been part of those decisions,” Obama wrote in the speech.

“And no matter how daunting the odds; no matter how much people try to knock her down, she never, ever quits. That’s the Hillary I know. That’s the Hillary I’ve come to admire. And that’s why I can say with confidence there has never been a man or a woman more qualified than Hillary Clinton to serve as President of the United States of America.”

Former President Bill Clinton delivered a speech Tuesday intended to promote his wife’s likability, focusing on her as a college student, young mother and grandmother. Obama is expected to talk more about Hillary’s policy chops.

“Obama has to be the guy on policy,” said Hank Sheinkopf, a longtime Democratic political consultant. “Economics and security.”

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Sheinkopf said the president likely will touch on the nation’s economic troubles when he took over in 2009 and the gains since, making the case that Clinton is better than Trump to continue the trend. And the incumbent would help Clinton tremendously if he said she’s a tough leader on national security.

“If he really wants to help her, he’ll say she was in the room with me when the decision was made to kill Osama bin Laden and she will have the same determination when she leads this nation,” Sheinkopf said.

Obama’s speeches at the past three DNCs have been huge successes among the party faithful and, some say, swing voters. In 2004, he was a Senate candidate who burst on to the national scene in a well-received address. His speeches in 2008 and 2012 are sometimes credited with getting him elected and then re-elected.

Democrats are hoping he will do the same for Clinton. Aides have said the president has been personally working on Wednesday night’s speech for weeks.

On Sunday, Obama told CBS he wasn’t “bosom buddies” with Clinton, but said there’s no one more knowledgeable about foreign and domestic policy. He called her “tough as nails.”

“I think that I’ve got a pretty clear-eyed sense of both her strengths and her weaknesses,” Obama said. “And what I would say would be that this is somebody who knows as much about domestic and foreign policy as anybody. . . . She’s not always flashy. And there are better speechmakers. But she knows her stuff.”

Vice President Joe Biden and former New York City Mayor Michael Bloomberg will deliver Clinton endorsement speeches before the president speaks.