Dr Nik Johnson is the new Mayor of Cambridgeshire and Peterborough.
When the final votes were tallied, he had 113,994, compared to Tory Mayor James Palmer with 108,195.
The contest went to the wire and was only decided after Peterborough released its second preference votes to secure a Labour victory.
With only Peterborough left to declare its second preference choices, Labour could within the next few minutes pull off the political upset of the decade in Cambridgeshire.
In the past few minutes, as Cambridge declared its second preference votes, Labour has gone ahead for the first time
The battle is getting extremely close as second preference votes are heading to Labour in growing numbers.
Dr Nik Johnson has been slowly narrowing the gap and with Cambridge City and Peterborough to declare, he could be poised to produce the political sensation of the year.
With second preference votes now in Dr Johnson has 102,173 votes compared to Mayor James Palmer for the Conservatives who has 104,232.
Cambridge and Peterborough will decide the outcome - it is a case of winner takes call
And as four areas declare, the gap between Labour and Tory incumbent James Palmer is narrowing.
Dr Nik Johnson is the Labour challenger to Tory incumbent James Palmer.
The third candidate, Aidan Van de Weyer for the Lib Dems, came third and is eliminated.
It means second preference votes now matter.
First count declarations for
Voting after first round
Johnson (Labour and Co-Operative Party) 76,106
Palmer (Conservative) 93, 942
Van de Weyer (Liberal Democrats) 61,885
Johnson and Palmer will now move to the second count.
SECOND ROUND RESULT FROM EAST CAMBS
Second round result from East Cambs:
Johnson (Labour and Co-Operative Party) 4929
Palmer (Conservative) 1444
The result will be declared later this afternoon.
Counting has also begun for the police and crime commissioner election.
POLICE AND CRIME COMMISSIONER RESULTS
FENLAND
PCC ELECTION: First round result from Fenland:
Massey (Labour) 4,553
Morris (Reform UK) 1,148
Moss-Eccardt (Liberal Democrats) 2,100
Preston (Conservative) 14,437
HUNTINGDONSHIRE
PCC ELECTION: First Round result from Huntingdonshire District:
- Massey (Labour Party): 11,204
- Morris (Reform): 1,993
- Moss-Eccardt (Liberal Democrats): 8,330
- Preston (The Conservative Party: 24,385
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