The race for the Ontario Progressive Conservative leadership is a toss-up between Christine Elliott and Doug Ford, a new poll suggests.

After weighting responses by riding — each riding will be worth up to 100 points when the votes are counted — the poll shows Elliott with 35.2 per cent to 34.9 per cent for Ford.

Caroline Mulroney trails in third with 17.3 per cent, followed by Tanya Granic Allen at 12.5 per cent.

The survey was conducted between March 1 and 8 by Mainstreet Research, which interviewed 18,308 PC party members through interactive voice response and via email. Mainstreet obtained three copies of the names of members eligible to vote in order to verify the accuracy of the list. The survey was not sponsored by any third party.

Among all members, Elliott's advantage was wider. She had 38 per cent support among decided PC members, with Ford at 32 per cent, Mulroney at 17.5 per cent and Granic Allen at 12 per cent.

Jen Gerson, Jason Markusoff, Aaron Wherry and Marie Vastel discuss. 10:39

The poll shows that Elliott has strong second-choice support from voters who would cast their ballots for Mulroney, while Ford is the favourite choice of Granic Allen's supporters.

This could lead to a very close result on the final ballot.

Mainstreet finds that 66 per cent of Granic Allen's supporters would rank Ford as their second choice, with only 11 per cent selecting Elliott. Another 17 per cent would not rank any candidate as their second choice, which would lead to their ballots being discarded after Granic Allen's elimination.

Support from Granic Allen's voters would boost Ford into first place on the second ballot — 44 per cent to 37 per cent for Elliott and 19 per cent for Mulroney — but Elliott's strong support among Mulroney's voters would help her on the third and final ballot.

According to the poll, 62 per cent of Mulroney's voters would rank Elliott second, with just 16 per cent selecting Ford. That would narrowly push Elliott to 51 per cent support on the final ballot to 49 per cent for Ford.

That is a close margin — and considering the potential margin of error in the survey and a voting system that awards equal weight to each riding regardless of the number of members it has (unless it has less than 100), the poll suggests that both Elliott and Ford have almost even chances of winning on Saturday.

Voting ended at noon today, though a court in Toronto is hearing an injunction aimed at extending the voting period by another week. The winner will be announced in Toronto on Saturday. The event will be covered live on CBCNews.ca and CBC News Network starting at 1 p.m. ET.