Murphy surged out ahead on Wednesday afternoon thanks to Mercer County 

Dems hope the remaining mail-in ballots to count will get Murphy over the line

Some counties have already faced delays in counting ballots because of issues with new voting machine technology and 'poll worker error' 

Murphy has polled ahead of Ciattarelli for months leading up to the election 

But on Tuesday night, as polls closed, Ciattarelli was leading by just 1,200 votes 

In the early hours Wednesday, Associated Press said race was too close to call 

A Democrat hasn't won re-election as New Jersey governor since 1977

Murphy was Barack Obama's United States Ambassador to Germany

Jack Ciattarelli is a businessman and former state lawmaker