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New numbers from Michigan State University show Hillary Clinton and Bernie Sanders are neck and neck among Democratic voters.

"For the Democrats the splits are really about age," said Matt Grossmann, the director of the Institute of Public Policy and Social Research. "Middle-aged people don't have any perceivable shift. We see young people overwhelming support Bernie Sanders, old people overwhelmingly support Hillary Clinton."

Which means young voter turnout will make all the difference.

"The main responsibility for the Sanders campaign is to get people who don't normally participate in the primaries out to vote," said Grossmann.

Clinton is leading this poll by 5 points with 51.9 percent, while Bernie has 46.9 percent.

"There are a lot of people who decided not to vote for Donald Trump, but they haven't all decided to vote for the same candidate," said Grossmann.

Which is why Trump is leading with 36.1 percent, followed by Ted Cruz at 19.5 percent, Marco Rubio at 18.1 percent, and finally John Kasich at 8.9 percent.

"Some people are trying to vote strategically for the candidate most likely to beat Trump, but don't know who that is," explained Grossmann.

He says people that have less education are more likely to support Trump but less likely to turnout to vote.

"People as they get closer to vote start to learn more that they like or dislike about candidates, and that might reduce Trump support," said Grossmann.

Support that could go to another Republican candidate.