What will it take for Democrats to win the Senate?

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An unexpected announcement could bring Democrats a huge opportunity in their quest to take control of the senate. Republican Senator Johnny Isakson is retiring at the end of the year - setting the stage for two competitive races in Georgia, an emerging swing state. But is it the opportunity Democrats hope it is? NBC News senior political editor, Mark Murray, and former senior advisor to Jeb Bush, Michael Steel, join Craig Melvin to break it all down.