The four leading candidates to become mayor of Montreal are in the midst of a series of one-on-one round robin debates.

On Monday Richard Bergeron faced off against Denis Coderre, while Melanie Joly debated Marcel Coté.

In the first round Bergeron, leader of Projet Montreal, attacked Coderre's integrity, saying it was a poor decision to surround himself with so many former members of Union Montreal, the party that was led until last year by Gerald Tremblay.

Bergeron also used Coderre's history as a federal politician against him, saying some of the donations he received were unethical. Coderre responded that every donation he received was always legal.

After the debate Coderre dismissed the attacks.

"They try to attack me personally but I'm going to stick to my plan," said Coderre. "People know me, I'm going to be for them. I have the leadership I have the team."

Bergeron said he was surprised that Coderre is still the frontrunner, branding him as the second coming of Gerald Tremblay.

Tuesday Coté and Coderre will debate each other while Joly squares off against Bergeron.

On Wednesday Coderre will face Joly, while Coté and Bergeron square off.