The Tories will not back down on RER, in fact in keeping with it's subway, subway, subway mantra, I could see the Tories doubling down on the effort to make the entire RER system grade separated and hence becoming a Metro/subway and labelling it as such. "Look Mom, the Liberals are only giving you 200km of GO trains but we will give you 200 km of subways". For the vast majority of Canadians {and the US for that matter} the idea of RER/suburban rail/S-Bahn is a rather nebulous concept. The average person {and hence voter} views it as just more frequent GO commuter rail service but everyone knows what a subway/Metro is and view it as the Gold Standard of public transit. The Tories will proclaim to those crucial 905 voers that the Liberals are only giving you more GO service while we will bring the subways to the suburbs.