Ottawa's mayor has thrown his weight behind the "Lansdowne Live" proposal to redevelop Lansdowne Park, dealing a potentially fatal blow to hopes for a Kanata soccer stadium.

Larry O'Brien was telephoning city councillors Saturday to bolster support for the plan, spokesman Eric Lamoureux told CTV Ottawa.

O'Brien tried his best to bring the competing groups together but could not convince Ottawa Senators owner Eugene Melnyk, proponent of a west-end soccer facility, to collaborate with Lasndowne developers, Lamoureux added.

If necessary, more meetings between O'Brien and councillors will be held Sunday. Public delegations to council about the stadium proposals are scheduled to begin Monday.

Minto boss Roger Greenberg, one of the Lansdowne proponents, told media outlets on Friday that their proposal remains the City of Ottawa's best option. He threatened to kill the project if city council delayed making a decision at Wednesday's meeting.

Greenberg and his team -- which includes Ottawa 67's owner Jeff Hunt and developers Bill Shenkman and John Ruddy -- want to build a multi-use, open-air stadium at Lansdowne Park, which would bring a CFL franchise to Ottawa.

Meanwhile, Melnyk has drafted his own plans to build astadium and entertainment complex near Scotiabank Place in Kanata, which would serve as a base for a potential Major League Soccer franchise.