(AP Photo/Mary Altaffer)
Donald Trump.

Donald Trump entered into general-election mode Tuesday night, seeking a pivot to unite the Republican Party against a common foe as it declared him its presumptive presidential nominee.

"We're going after Hillary Clinton," Trump said during a victory speech at Trump Tower in New York.

"She will not be a great president. She will not be a good president. She will be a poor" president, he said of the Democratic frontrunner, his likely opponent in the general election.

After winning the Indiana primary Tuesday and knocking Ted Cruz out of the Republican race, Trump prepared for the road ahead, as did the party he is now set to lead.

Republican National Committee Chairman Reince Priebus called Trump the "presumptive nominee" and called for party unity on Tuesday.

"@realDonaldTrump will be presumptive @GOP nominee, we all need to unite and focus on defeating @HillaryClinton," he tweeted shortly after Cruz announced he was leaving the race.

In a nod to the anti-Trump movement that branded itself as #NeverTrump, Priebus added a hashtag: #NeverClinton.

Trump's victory speech, made from Trump Tower in New York, was without the insults trademark to his campaign; he congratulated Cruz on a race well run and called him a "hell of a competitor." And he keyed in on Clinton.

"We're going to win big, and it's going to be America first," Trump said.

"This country, which is very, very divided in so many different ways, is going to become one beautiful and loving country," he later added.

Having secured at least the vast majority of 57 delegates up for grabs in Indiana, Trump now needs fewer than 200 delegates to secure the nomination ahead of the party's July convention. Gov. John Kasich of Ohio is the lone remaining candidate facing Trump in the Republican race, but he is fourth in the delegate count.

Clinton's campaign has already taken notice of Trump's imminent grasp on the Republican nomination.

John Podesta, Clinton's campaign chair, delivered the campaign's first direct general-election shot at Trump. Podesta said Trump wasn't prepared to keep the country safe and improve conditions for middle America.

"Throughout this campaign, Donald Trump has demonstrated that he's too divisive and lacks the temperament to lead our nation and the free world," Podesta wrote in a statement. "With so much at stake, Donald Trump is simply too big of a risk."

"While Donald Trump seeks to bully and divide Americans, Hillary Clinton will unite us to create an economy that works for everyone," he later wrote.

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