Poll put Libs a nose in front in Bennelong

As voters prepare to cast their ballots in Sydney's Bennelong by-election, the latest Galaxy poll puts Liberal John Alexander a whisker ahead of Labor's Kristina Keneally.

The crucial vote will decide whether the federal government keeps its wafer-thin parliamentary majority, with a loss in Bennelong leaving the government with only 75 seats out of 150 in the lower house.

The Galaxy poll, published in The Daily Telegraph, put Mr Alexander's primary vote at 40 per cent, two percentage points ahead of the former NSW premier, Ms Keneally.

On a two-party preferred basis the Liberals have edged ahead to 51 per cent, for Labor's 49 per cent.

It's predicted to be a close result, but preferences are likely to get the former professional tennis player turned Liberal MP over the line, the paper reports.