OTTAWA -- The Senate voted Wednesday to allow suffering Canadians who are not near death to seek medical help to end their lives, knocking out the central pillar underpinning the federal government's proposed new law on medically assisted dying.

Senators voted 41-30 to amend Bill C-14, deleting the requirement that a person's natural death must be "reasonably foreseeable."

The amendment replaces the eligibility criteria in the bill with the much more permissive criteria set out in last year's landmark Supreme Court ruling, which struck down the ban on assisted dying.

That sets the Senate on a potential collision course with the government.

Justice Minister Jody Wilson-Raybould signalled earlier Wednesday that the government is unlikely to accept such an amendment.

"We've worked incredibly hard on this piece of legislation to ensure that we find the right balance and we're confident that we've found the right balance between recognizing personal autonomy and protecting the vulnerable," she said outside a Liberal caucus meeting.

"If we were to consider removing reasonable forseeability, that would broaden the regime, the balance that we have struck."

She added: "There would need to be additional safeguards ... This is an incredible and momentous change in our country and we're confident what we put forward is the right choice for Canada right now. It's a first step."

In anticipation of that reaction, the amendment, proposed by Sen. Serge Joyal and passed late Wednesday night, is intended to go hand-in-hand with another amendment, to be proposed by Conservative Senate leader Claude Carignan,

Carignan's amendment would impose an additional safeguard, requiring a judge to sign off on an application for assisted dying by anyone who is not close to death. It is to be debated and voted upon separately.

The near-death proviso in the bill has been widely condemned by legal and constitutional experts who maintain it renders the legislation unconstitutional and flies in the face of the Supreme Court ruling.

C-14 would allow assisted dying only for consenting adults "in an advanced stage of irreversible decline" from a serious and "incurable" disease, illness or disability and for whom natural death is "reasonably foreseeable."

That's more restrictive than the Supreme Court's directive that medical assistance in dying should be available to clearly consenting, competent adults with "grievous and irremediable" medical conditions that are causing enduring suffering that they find intolerable.

Senators voted for Joyal's amendment despite a warning from Sen. Peter Harder, the government representative in the upper house, that it "largely guts the bill."

Joyal and others argued that the amendment was necessary to ensure the bill is constitutional.

"I believe this bill is deeply flawed and I can not support it as it stands because, in my view, it is unconstitutional," said Sen. James Cowan, leader of independent Liberal senators.

Others cast the amendment in terms of ensuring compassion for those who are suffering intolerably.

Conservative Sen. Linda Frum said she doesn't believe that Parliament has an obligation to "act as the drafting committee of the Supreme Court." But she added: "I do believe that there are fates worse than death, such as unbearable and excruciating pain that promises to last for years on end, grievous physical and mental suffering, the loss of human dignity."

"It's possible for all of these conditions to exist separately from a reasonably foreseeable death."

The amendment puts the Senate on the path towards a potential impasse with the House of Commons, which must decide whether to accept or reject any changes proposed by the upper house.

If the Commons rejects the amendment, Carignan has predicting the Senate will "insist" upon it.

There is no mechanism for breaking a deadlock between the two houses of Parliament.

Theoretically, the Senate could repeatedly send the bill back to the Commons with the same amendment, until one chamber or the other gives in.

The two chambers could also agree to hold a "conference" -- a procedure to resolve an impasse that has not been used in some 70 years.

An impasse between the chambers would prolong the time in which Canada is without a criminal law governing medical assistance in dying. When the top court struck down the ban on assisted dying, it gave Parliament a year, later extended by four months, to craft a new law. That deadline passed on Monday.

In the absence of a law, the procedure will be governed by the eligibility criteria spelled out by the Supreme Court, guidelines issued by medical regulators in each province and any rules set by provincial governments.