After Tuesday night’s primaries in six states, both parties now have presumptive nominees for president.
But there are still three candidates in the race.
Hillary Clinton celebrated the historic milestone during a speech in New York, Tuesday night.
"The first time in our nation's history that a woman will be a major party's nominee for President of The United States.”
It didn’t take long for Clinton and Donald Trump to turn their sites on each other.
They both began courting supporters of Bernie Sanders, who says he is not bowing out yet.
"We take our fight for social, economic, racial and environmental justice to Philadelphia,” Sanders said in California.
Many Sanders supporters say they will refuse to back Hillary Clinton if Sanders is no longer in the race.
Trump capitalized on that sentiment.
"To all of those Bernie Sanders voters who have been left out in the cold by a rigged system of superdelegates, we welcome you with open arms, believe me,” Trump said to supporters.
Seth Masket is a political science professor at the University of Denver.
He says Sanders will eventually throw his support behind Clinton, but it may not be immediately.
“They fought it out and now they're in the process of coming back together over that,” Masket said. “This is basically what a party does in a normal presidential cycle.”
Sanders is set to meet with President Obama on Thursday.
Masket said he may be using his still sizable support to sway Clinton’s campaign.
“Maybe for some policy concessions or so he can play a larger role in deciding what the party will stand for and what the next administration should look like should the Democrats win,” he said.
Sanders says he plans on campaigning through next Tuesday’s final primary in Washington, D.C.
There are reports he plans on laying off more than half of his staff.