The seat of Blain is held by NT Chief Minister Terry Mills, while Sanderson is a key seat in Darwin's northern suburbs held by the CLP, and Brennan is a safe CLP seat held by Housing Minister Peter Chandler.
The poll of 437 voters between March 1-6 comes after an aborted leadership challenge to Mr Mills from Attorney-General John Elferink last month and finished on the day Transport Minister Adam Giles challenged Mr Mills on Wednesday.
The CLP performed badly in a recent by-election, where the ALP received almost 70 per cent of the two-party vote, and has come under fire for substantial spending cuts and power price rises.
But the poll showed voters still think Mr Mills would be a better chief minister than Labor leader Delia Lawrie.
The poll showed 38 per cent of voters thought Mr Mills was a better choice compared to 37 per cent who preferred Ms Lawrie, with 25 per cent uncommitted.