Trudeau says the Conservatives have become a one-trick attack machine to distract from what he called its mediocre record on the economy and other issues.
He says the Tories are using public money to mail out household flyers that distort the truth about him.
He made the comments while campaigning alongside Liberal candidate Yvonne Jones for the May 13 byelection in Labrador.
Government House Leader Peter Van Loan says the flyers fall within parliamentary spending rules.
Trudeau says the multi-pronged attack on his leadership credentials is proof that Conservatives are worried voters are ready for a more positive approach.
The byelection was called after Conservative incumbent Peter Penashue (pen-ASH'-away) resigned over illegal donations in the 2011 campaign.
NDP candidate Harry Borlase is also running to replace Penashue.