Hillary Clinton 'Perplexed' by Bernie Sanders's Superdelegate Plan

Hillary Clinton and Bernie Sanders speak simultaneously during their debate in Flint, Michigan, on March 6. The final six states are holding voting contests Tuesday in what could effectively end the 2016 primary race. Jim Young/Reuters

Shortly before she was declared the Democrats' presumptive nominee by the Associated Press Monday night, Hillary Clinton said she was "perplexed" about challenger Bernie Sanders's mission to persuade superdelegates to support his campaign.

"He basically seems to be suggesting that superdelegates should overturn the will of the people. That is just hard for me to understand. It's never happened before. It's not going to happen this time," Clinton said during an interview with MSNBC that aired Monday night.

"The sooner we unify and make our case against Donald Trump, the better off the Democratic Party will be," she added, referring to her likely opponent in the general election.

On the eve of the final six state contests of the 2016 primary season, the AP named the former secretary of state as the Democrats' presumptive nominee, citing her weekend Puerto Rico primary win and a burst of last-minute support from superdelegates. This reported delegate count now makes her the first woman to capture the presidential nomination of one of the country's major political parties.

Shortly after the AP published its report, Clinton responded by saying she was "flattered" that she had secured the required minimum of 2,383 delegates, but said she remains focused on winning Tuesday's voting contests, most notably in delegate-rich California and New Jersey. She has spent much of the past several weeks pushing aside Sanders while simultaneously making verbal jabs at Trump.

Throughout the primaries, Sanders has said he won't exit the race until residents in every state have voted, or until the Democratic National Convention at the end of July. But at a Monday press conference, he stressed the importance of defeating Trump in the general election, and reiterated his belief that he is the stronger Democratic candidate to accomplish that task. Later that evening, at a rally in San Francisco, he acknowledged that this week's primaries and caucuses are make-or-break contests for his campaign.

"Tomorrow, in the most important primary in the whole Democratic nominating process, we're going to win here in California," he said in front of thousands of supporters at the campaign event, which was headlined by the Dave Matthews Band.

Meanwhile, Clinton is reiterating that the Democrats need unity. It was eight years ago on June 7 that she conceded to and threw her support behind her Democratic rival, freshman Senator Barack Obama. Clinton has recently pointed out that the race was significantly closer in 2008 than it is now between her and Sanders.

"But I took the position that, you know, he had a lead in the pledged delegates," Clinton said about Obama, during the MSNBC interview. "I withdrew and I also endorsed him, and I knew how important it was to unify the Democratic Party. I think it's equally important this time around."

Clinton's reported clinching of the nomination came because of support from superdelegates—unelected delegates who can support any contender for the presidential nomination at the convention. But Sanders and his campaign have pushed back on this, and he didn't acknowledge the report of Clinton's victory during his rally in San Francisco. Instead, the Vermont senator warned the media against rushing to declare the nominee ahead of the convention in Philadelphia, because superdelegates could change their opinions before they cast their votes.

In an effort to bring together Democrats, Clinton said she plans to contact Sanders Tuesday night. "Our campaigns are certainly talking," she told MSNBC.

Obama called Sanders Sunday to discuss the primary, and the two men reportedly spoke for 45 minutes. Various media reports indicate the president is ready to endorse Clinton and could announce his decision as soon as this week.

Later on Tuesday, Clinton will hold a rally at her campaign headquarters in New York's Brooklyn, and Sanders will speak at an event in Los Angeles before returning to his home in Burlington, Vermont.