Three former Rudy Giuliani aides have formed a political-action committee to boost mayoral hopeful Joe Lhota, who’s facing a significant challenge from billionaire John Catsimatidis in the Republican primary.

The New Yorkers for Proven Leadership PAC is the brainchild of Michael McKeon and Chris Henick, advisers to Giuliani’s 2008 presidential campaign, and Ryan Medrano, who worked on Giuliani’s campaigns and at his security firm.

“We’re New Yorkers who want to see the leadership that Rudy and Mike Bloomberg brought to the city continue,” McKeon told The Post.

How much the group will spend is unclear. Giuliani will likely stay on the sidelines but could help raise money.

Lhota, a Giuliani deputy mayor, has been outspent by Catsimatidis, who has pumped approximately $4 million of his own money into the campaign.

Catsimatidis spokesman Rob Ryan said, “Joe Lhota is slipping in the polls and can’t raise the money he needs to stay competitive, so now he’s praying that his deep- pocket cronies will bail him out.”