wedge issue

American  

noun

1. an issue that divides or causes conflict in an otherwise unified group.

   Abortion is a wedge issue for the Republican Party.

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wedge issue British  

noun

1. an issue that is likely to cause division between the members of a group

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Etymology

Origin of wedge issue

First recorded in 1990–95

Example Sentences

For those who don’t remember, Thompson was the attorney who led the charge against violent video games and helped morph a fringe topic into a dominant wedge issue of the mid-2000s.

From The Verge

Vaccine mandates have emerged as an early wedge issue in Canada's snap federal election - called by Prime Minister Justin Trudeau two years before his current mandate expires.

From BBC

Trudeau on Sunday telegraphed that the Liberals are looking to position coronavirus vaccines as a wedge issue.

From Washington Post

Vaccine mandates could prove to be a campaign wedge issue, says Mr Colleto.

From BBC

Adam Spiker, executive director of the nonprofit Southern California Coalition, the Southland’s largest marijuana trade association, said cannabis is a wedge issue that “certainly can exacerbate the political divide.”

From Los Angeles Times