Prime Minister Stephen Harper will meet today with Saskatchewan Premier Brad Wall to discuss forest fires, but he may find himself trying to douse the flames of another disaster: the Senate.

Proximity to Wall, who champions abolition of the scandal-plagued upper house, will doubtless raise questions about Harper's own plans for the discredited chamber.

The prime minister threw in the towel last year on his three-decade crusade for an elected Senate after the Supreme Court of Canada ruled that reforming the chamber would require a constitutional amendment approved by at least seven provinces with 50 per cent of the population (the so-called 7/50 amending formula.)

The top court set the bar even higher for abolition, Harper's fallback position should reform prove impossible. Getting rid of the Senate altogether, the court advised, would require unanimous provincial consent.

At the time, Harper said the court had essentially pronounced "that significant reform and abolition are off the table."

"We know that there is no consensus among the provinces on reform, no consensus on abolition, and no desire of anyone to reopen the Constitution and have a bunch of constitutional negotiations."

Earlier Friday, Justice Minister Peter MacKay agreed that last year's Supreme Court decision essentially ruled out abolition. MacKay said his 18 years in politics and previous career as a lawyer told him the likelihood of getting unanimous provincial consent is "virtually zero."

Empty chairs pile up

A year earlier, as the Senate was engulfed in scandal over allegedly improperly claimed living and travel expenses, Harper stopped appointing senators. There are now 22 vacancies, which the prime minister has shown no inclination to fill any time soon — almost certainly not before the Oct. 19 federal election.

However, the Supreme Court has also made it clear that allowing vacancies to pile up can't go on indefinitely since it would amount to abolition by stealth.

Section 42 of the Constitution specifies that the powers of the Senate and the number of senators for each province are among those things that can be changed only by a 7/50 amendment, the court noted in its 2014 landmark ruling.

That section "presupposes the continuing existence of a Senate and makes no room for an indirect abolition of the Senate," the court said. "It is outside the scope of s. 42 to altogether strip the Senate of its powers and reduce the number of senators to zero."

As the election looms and the Senate scandal continues to go from bad to worse in the wake of a devastating audit that flagged inappropriate expense claims by 30 more senators, Harper's inaction has become increasingly untenable.

Wright testimony expected Aug.12

The pressure to articulate some sort of plan is likely to increase next month when the fraud and bribery trial of disgraced Sen. Mike Duffy resumes. Harper's one-time chief of staff Nigel Wright is slated to take the stand to explain his role in giving Duffy $90,000 to repay his disputed expense claims.

Harper's main opponents have plans for the upper chamber: NDP Leader Tom Mulcair is vowing to abolish the Senate, despite the constitutional hurdles; Liberal Leader Justin Trudeau has booted senators from his party's caucus and is promising, if elected, to create an independent advisory body to recommend non-partisan nominees to the Senate.

Harper has accused Mulcair of promising abolition, "knowing that isn't going to happen" because too many provinces, including Quebec and Ontario, don't support it. And he's accused Trudeau of wanting to set up an unelected, unaccountable body to recommend appointees to the unelected, unaccountable Senate. He's also rejected calls to free his own Conservative senators to sit as independent senators.

Having ridiculed his opponents' alternatives, he's left himself little room to propose anything other than the status quo.

With a file from CBC News