It can't be officially signed until after the election, but they can still negotiate. And all three parties, according to the article, are in support of the agreement.
"Despite the government’s attempt to grant itself the power to continue to negotiate the TPP during an election campaign, there are reasons to doubt that it can effectively do so. First, while there would seemingly be no problem with ensuring Canada remains at the negotiating table, committing to significant policy changes would go well beyond the description of a caretaker government that should be largely limited to “routine” activities.
.. Without a government mandate, Canadian negotiators simply can’t provide other TPP countries assurances that concessions made today will last beyond October 19th."
Nitpicking: It can probably be signed, but cannot be ratified. Ratification makes the treaty binding, signing does not, but I imagine it may be very difficult to re-open negotiations after signing.
"Despite the government’s attempt to grant itself the power to continue to negotiate the TPP during an election campaign, there are reasons to doubt that it can effectively do so. First, while there would seemingly be no problem with ensuring Canada remains at the negotiating table, committing to significant policy changes would go well beyond the description of a caretaker government that should be largely limited to “routine” activities.
.. Without a government mandate, Canadian negotiators simply can’t provide other TPP countries assurances that concessions made today will last beyond October 19th."