New South Wales Opposition Leader Barry O'Farrell is lying low after posting an embarrassing message yesterday morning on the social networking site Twitter.

Believing he was sending a private message to journalist Latika Bourke's Twitter account, Mr O'Farrell opened up on his thoughts about the delay on candidate selection.

With confirmation of a federal election possibly just days away, the Liberal Party is yet to select its candidates for the federal seats of Greenway and Parramatta.

It was supposed to be a "deeply off the record" direct message, but it had been re-tweeted by Twitter users before he had the chance to delete it.

"Deeply off the record - I think the timetable and struggle to get candidates reflects internal poll - pre and post the ranga," he tweeted, a reference to Prime Minister Julia Gillard.

Mr O'Farrell, who recently debated New South Wales Premier Kristina Keneally on Twitter, has since deleted the tweet.

He is not commenting on the Twitter gaffe - leaving it to the Nationals Leader Andrew Stoner.

"There's a few pitfalls involved, I think Barry has learned one of those pitfalls but we all make mistakes," he said.

Ms Keneally weighed in from China, saying she is certain Mr O'Farrell is very embarrassed.

Parramatta is held by Labor on a margin of almost 10 per cent while Greenway is up for grabs after boundary redistributions. It is on a notionally Labor margin of 5.7 per cent.