Minutes before her address declaring victory as the Democratic presidential nominee Tuesday evening, Hillary Clinton was worried she might not make it through her prepared remarks without crying.

“I was overwhelmed,” Clinton said in an interview with The Washington Post on Wednesday.

“It just was a sense of momentous historic experience — that I was part of it and it really was hard to actually, you know, make sense of it,” Clinton said, marvelling a day later at the sight of thousands of supporters crowded into a Brooklyn warehouse to celebrate.

“I was worried that if, when I went out to speak, just the emotion of the moment would be so intense that I might have trouble getting through the speech itself. So I did have to collect myself and try to get prepared.”

Clinton spoke by telephone a day after becoming the first woman in U.S. history to be the presumptive leader of a major-party presidential ticket. In her victory address on Tuesday, Clinton claimed the mantle in the names of suffragists and others who went before her.

On the night six states including California and New Jersey went to the polls, Sen. Bernie Sanders (I-Vt.) vowed to continue "the struggle," even as rival Democratic presidential candidate Hillary Clinton had pivoted to thanking supporters and slamming Republican Donald Trump. (Sarah Parnass/The Washington Post)

[The full transcript: The Hillary Clinton interview]

She spoke quietly at first. Supporters at the Brooklyn speech screamed as Clinton spread her arms in a gesture of triumph and gratitude. Some wept.

She said Wednesday that she had to work especially hard to keep her composure during a long passage crediting her late mother, Dorothy, with setting an example of hard work and kindness.

“I practiced the part about my mother several times, because I teared up every time I practiced it. And I tried to get myself so that I could be, you know, a little more used to saying it. And it still was for me personally one of the most extraordinary and meaningful public experiences I’ve ever had.”

In her first Post interview since launching her campaign 14 months ago, Clinton expressed cautious hope that rival Bernie Sanders, whose candidacy produced an unexpectedly hard-fought nominating contest, would soon rally behind her. And she left open the possibility that one of his chief demands — a change in the Democratic Party’s system of superdelegates — might be met.

Clinton fiercely denounced Republican opponent Donald Trump for what she said are racist views. She stopped short of labeling him a racist.

“I don’t know what’s in his heart. I have no way of telling that,” Clinton said. “I can just say that if you look at what he’s been proclaiming since he started the campaign, he has been engaging in divisive and prejudiced attacks against people.”

View Graphic Donald Trump vs. Hillary Clinton on the issues

Clinton is expected to formally become the nominee at the Democratic Party’s convention next month in Philadelphia. She begins general-election campaigning in earnest next week, with visits to the battleground states of Ohio and Pennsylvania. She has started campaigning directly against Trump, calling him dangerous and unfit to lead the country.

Trump’s complaints about a U.S.-born federal judge of Mexican heritage prompted some of Clinton’s most pointed criticism of Trump to date. The episode allowed her to paint Trump as racially insensitive just as she was making an important appeal to Hispanics in the run-up to Tuesday’s primary in California, where Hispanics are 40 percent of the population.

“And I think part of the reason he launched that attack using the racist language he did was to divert attention from the scam that is Trump University,” she said. “Which has been called a fraudulent scheme by officials on the staff of Trump University. And then he doubled down, saying he wasn’t sure a Muslim judge could be impartial, given his support for banning all Muslims from coming to the country.”

Part of Democrats’ strategy will be to try to allow Trump to dig holes for himself, as Clinton allies think he did with the controversy over the judge.

Trump and Clinton are roughly tied in the RealClearPolitics average of recent national polls, with Clinton ahead by just two percentage points. Many of those surveys were conducted before the judge controversy, which has led many national Republican figures to condemn Trump’s comments even if they do not disavow him as the presumptive GOP presidential candidate.

“Even though I can’t say what’s in his heart, if you say someone can’t do their job because of their heritage, that is certainly a racist attack,” Clinton said. “And it’s just plain wrong. It has no place in our politics. And as we have seen in the last week, a lot of Republicans, prominent Republicans, have rejected that and distanced themselves from it.”

Clinton ended up winning California handily Tuesday after a primary battle that was more difficult and divisive than predicted. A Sanders victory in California would not have changed the fact of Clinton’s overall victory Tuesday but would have blotted her success with a reminder of how many young and very liberal Democrats are not supporting her.

Trump had secured the Republican nomination weeks before, while Clinton was waging a fight with two opponents. Some Democrats are worried about the toll the long campaign took on Clinton’s standing nationally — and about the difficulty she may have uniting Democrats behind her.

“We’ve had a tough-fought race, and I, you know, admire his energy, his determination and commitment,” Clinton said of Sanders.

“I am certainly reaching out. Our campaigns are talking about how we can be unified, against the threat that Donald Trump poses to our future, and I want to unite the party and the country,” Clinton said. “We’ve got to do that to run the most effective race we can against Trump, and then we have to keep working to unify the country to get things done.”

Sanders did not concede after Tuesday’s round of primaries. He had said previously that he planned to take his cause to the convention.

Asked whether she is concerned that Sanders might not be a full partner once his candidacy is finally over, Clinton paused.

“I certainly hope he will be,” she said. “I think he and his supporters understand how much is at stake, that we need to join together to defeat Trump. And I’m going to really reach out, do everything I can to persuade him.”

As to the role of superdelegates, which Sanders has said contribute to a Democratic primary election system that he has called unfair, Clinton said she expects that the Democratic National Committee will at least consider a change.

“Yeah, we’re going to have a discussion. I think that’s something that the DNC does after every convention,” she said.

She did not express a direct personal opinion about whether the superdelegate system should be retained. Superdelegates are elected officials and party elders who, unlike pledged delegates won in state contests, can cast a vote for any candidate at the convention. Clinton had the support of a huge number of superdelegates throughout the campaign, adding to the obstacles facing any insurgent campaign to catch her.

Clinton said the FBI has not yet scheduled a time to interview her about the private email system she used at the State Department. The FBI is investigating whether classified information or national security were compromised through her use of a system that operated separately from the regular State Department email system.

“I certainly would like to see this wrapped up,” she said.