The senate can be reformed without opening the constitution.
I think May is winning by far.
Like what. You cant elect them without opening the constitution.
You can set up a multi-party committee to present multiple candidates to the PM for consideration. Rules for expenses and reporting the purposes of trips can be made more transparent. They could be required to sit on committees not paid extra for it. Rules for expulsion can drawn up and they should be very strict. Pensions can be cut.
Some of these the senate would have to agree to. They manage their own affairs. No province is forced to have elections for senators. If Harper could have done any of this he would have by now rather than face the electorate with the mess its in. The only changes Ive seen done was due to shaming the senators into doing it. It wasnt legislated into place.
There can be no elected Senate because it would give the Senate democratic legitimacy changing it's nature and the PM would have to accept an elected Senator if that became the norm. That doesn't mean an advisory committee would be rejected by the Courts.
Harper didn't want to reform the Senate he wanted a triple E senate or no senate.