The Republican National Committee (RNC) on Sunday disputed claims that Democratic presidential front-runner Hillary Clinton Hillary Diane Rodham ClintonJeff Flake: Republicans 'should hold the same position' on SCOTUS vacancy as 2016 Momentum growing among Republicans for Supreme Court vote before Election Day Warning signs flash for Lindsey Graham in South Carolina MORE will lock up the Democratic nomination after Tuesday's primaries.

"Hillary Clinton's nomination is not a done deal," RNC chief strategist Sean Spicer said in a memo.

ADVERTISEMENT

"A lot can change in 48 days, especially when the candidate who has the support of many of these unelected party bosses is still under investigation by the FBI."

Spicer pointed out that superdelegates will not officially count toward either candidate's delegate total until after they vote at the Democratic National Convention in July.

"That means according to the [Democratic National Committee] DNC's own rules, if Hillary Clinton doesn't hit 2383 pledged delegates after Tuesday's contests, any attempts to anoint Hillary Clinton the presumptive nominee will be premature," he said.

If the DNC declares Clinton the presumptive nominee after Tuesday's contests, he said, then it will be making clear that it doesn't want to give superdelegates the opportunity to change sides.

The RNC official called the superdelegate system "anti-democratic" and a "rigged method of choosing a nominee."

Spicer went on to question what would happen if Clinton's rival, Bernie Sanders Bernie SandersNYT editorial board remembers Ginsburg: She 'will forever have two legacies' Two GOP governors urge Republicans to hold off on Supreme Court nominee Sanders knocks McConnell: He's going against Ginsburg's 'dying wishes' MORE, "wins big on Tuesday."

"Bernie still has a puncher's chance to overtake her in the pledged delegate lead before the convention," he added.

He also referenced the many primaries Sanders has won without securing the support of the states' superdelegates.

"Should those party insiders do the right thing and support Sanders just like their constituents, perhaps Clinton’s claimed lead isn’t really what it seems," he said.

"The multitude of Sanders supporters who are upset about the rigged superdelegate system have pledged to make their voice heard at the Democrat convention. 74-year old Bernie Sanders is the oldest candidate in the race. But he could be a comeback kid this Tuesday."

Sanders has said he plans to stay in the race and fight for every delegate. He has been campaigning in California and has said he expects to do well in the delegate-rich state on Tuesday. Clinton has declared she will be the nominee, and a top adviser on Sunday said he expects Clinton will secure the nomination with delegates won on Tuesday.