Liberals are hoping to pin down Prime Minister Stephen Harper over where he stands on abortion in his G8 maternal-health initiative for the Third World.
The Opposition is to introduce a motion in the House of Commons on Tuesday demanding that the plan cover a "full range" of family-planning options, which would include contraception and abortion.
The Conservative government has been unclear about whether the plan will fund such options.
The motion says funding all options would be consistent with the policy of previous governments - both Conservative and Liberal - and with the approach approved by all G8 countries, including Canada, just last year.
The motion should pass easily with the support of all three opposition parties.
It could put the Conservatives in an awkward spot, forcing them to clarify the issue and potentially alienate one faction or another within the party.
The Harper government has sent mixed messages about the Prime Minister's decision to champion maternal and child health at June's G8 summit, which he is to host in Huntsville, Ont.
This week, Foreign Affairs Minister Lawrence Cannon said the initiative won't include family planning "in any way, shape or form."
But Mr. Harper and International Co-operation Minister Bev Oda later insisted they're open to considering all options, including contraception, for saving the lives of the world's poorest women.
They also said the government doesn't intend to reopen the abortion debate, which left some room for interpretation as to whether the government intends to continue funding family-planning organizations that advocate access to safe abortions.
Some pro-life groups have been urging Mr. Harper to use the opportunity to end funding for abortion advocacy groups - as was done in the United States under George W. Bush's administration.
The Liberal motion says the government should "refrain from advancing the failed right-wing ideologies" of the Bush era and be guided by scientific evidence "which proves that education and family planning can prevent as many as one in every three maternal deaths."