The opposition MPs who previously supported a Conservative bill to scrap the federal long-gun registry represent largely rural ridings, but they will face different pressures as they defend their vote on Wednesday on a motion to preserve it.
The 20 MPs - eight Liberals and 12 New Democrats - come from disparate parts of the country, won their seats with varying levels of support, and will have to explain their actions to different constituencies.
Three of the Liberals who voted last year for a Conservative private member's bill to scrap the registry are from Newfoundland and Labrador.
Scott Simms and Todd Russell won by wide margins in 2008. And Scott Andrews, who took 45.3 per cent of the votes in his constituency, would not seem to be in jeopardy of losing his seat in a province where Conservative support has fizzled.
But Newfoundland and Labrador has the highest per-capita number of firearms ownership in the country and the lowest rate of firearms-related gun crime. So making the case for keeping the registry is a challenge there.
Five of the New Democrats and another Liberal who previously voted for the bill are from Northern Ontario. Four of those NDP MPs and Liberal MP Anthony Rota say they will now vote for the motion to kill the bill.
Most of the Northern Ontario MPs say the gun registry is not a make-or-break issue in their ridings. And, like Newfoundland, their region shows little Conservative support.
Niki Ashton, the New Democrat who represents the riding of Churchill in Manitoba, won by a large margin in a constituency that has been held mostly by the NDP since 1979. She remains the big question mark going into Wednesday's vote.
On the other hand, some New Democrats took their seats by relatively slim margins in the last election and felt the Conservative candidate breathing down their necks.
They include Dennis Bevington in the Western Arctic and Jim Maloway in the Manitoba riding of Elmwood-Transcona. Neither has been willing to switch his vote to preserve the registry.
Keith Martin, the Liberal MP from Esquimault-Juan deFuca on Vancouver Island, won his seat by just 68 votes in 2008. But Mr. Martin feels he must vote with the Liberals, and if he loses his seat, so be it.
Editor's note An earlier version of this story said Ontario NDP MP Malcom Allen was not willing to switch his vote. In fact, he has. This version has been corrected.