Prime Minister Malcolm Turnbull has attacked Kristina Keneally's position on asylum seekers in his first appearance in the Bennelong byelection.
Labor's star candidate has been surging in the polls ahead of the byelection, which was called after incumbent Liberal John Alexander was forced to resign after being caught out in the citizenship scandal.
Mr Turnbull joined the campaign on Sunday and told voters to consider the former NSW premier's position on immigration as they prepared to vote on December 16.
"Kristina Keneally wants us to bring all of those asylum seekers from Manus [Island] to Australia," Mr Turnbull said in Sydney on Sunday.
"Now believe me, right now, the people smugglers are using Kristina Keneally's articles, her statements on this as a marketing tool to get people onto their boats to take them to sea....When the boats start again, if Labor were ever to get back into government, how many of those asylum seekers is she going to bring to Bennelong?"
Ms Keneally said Mr Turnbull was "making mischief" by suggesting her past statements on asylum seekers were out of line with Labor policy.
"The Prime Minister wants to make mischief with this issue because he doesn't have anything else to talk about. Nobody wants the people smugglers back in business. I completely support Bill Shorten and Labor's position on asylum seekers," Ms Keneally said.
Labor leader Bill Shorten's decision to draft Ms Keneally to run in the crucial Bennelong byelection has propelled Labor to within striking distance of winning the usually safe Liberal seat.
At the 2016 federal election Mr Alexander was comfortably returned with 59.7 per cent of the two-party-preferred vote.
The seat is held by a margin of 9.7 per cent.
At the end of the first week of campaigning Mr Alexander was ahead with 53 per cent compared to Ms Keneally on 47.
That represents a swing of almost 7 per cent away from the Liberal Party against the 2016 election result.
Although Mr Alexander is favoured to retain the seat based on his personal popularity and past conservative voting patterns Labor is investing heavily in the byelection campaign which it is trying to turn into a referendum on the performance of the Turnbull government.
With a one-seat majority in the House of Representatives, the Bennelong race could determine whether the embattled Coalition retains its position or is forced to rely on crossbenchers for confidence and supply.