Wyoming Senate candidate Liz CheneyElizabeth (Liz) Lynn CheneyThe Hill's Morning Report - Trump hews to NRA on guns and eyes lower taxes Dick Cheney to attend fundraiser supporting Trump reelection: report Steve King says 'left-wing media' and GOP leadership owe him apology after rape, incest comments MORE's (R) opposition to gay marriage is drawing criticism from her lesbian sister.

Cheney, running against Sen. Mike EnziMichael (Mike) Bradley EnziThe 23 Republicans who opposed Trump-backed budget deal On The Money: Fed poised to give Trump boost with rate cut | Parties unable to reach deal in Trump tax return lawsuit | New York opens investigation into Capital One data breach Outgoing Senate Budget chair unveils plans to replace Budget Committee MORE (R-Wyo.), reiterated on Sunday morning that she doesn't support gay marriage. That drew rebukes from Mary Cheney and her wife, Heather Poe.

Poe took to Facebook to rip Liz Cheney for her comments.

"I was watching my sister-in-law on Fox News Sunday (yes Liz, in fifteen states and the District of Columbia you are my sister-in-law) and was very disappointed to hear her say "I do believe in the traditional definition of marriage," she says in a Sunday afternoon post.

"Liz has been a guest in our home, has spent time and shared holidays with our children, and when Mary and I got married in 2012 — she didn't hesitate to tell us how happy she was for us. To have her now say she doesn't support our right to marry is offensive to say the least."

Mary Cheney shared that post, and added her own criticism.

""Liz — this isn't just an issue on which we disagree — you're just wrong — and on the wrong side of history," she writes.

Liz Cheney said Sunday morning that she loves Mary and Heather "very much. ... This is just an issue on which we disagree."

Liz Cheney is in a tough spot on the issue. A socially conservative outside group run by former Arkansas Gov. Mike Huckabee's (R) daughter has been airing ads accusing her of supporting gay marriage. She's responded by saying she believes the issue should be left to the states and that she personally opposes allowing same-sex couples to marry, a position at odds not only with her sister but with her father, former Vice President Dick Cheney (R), who supports gay marriage.

A recent poll released by the outside group opposing Cheney found her trailing Enzi by more than 50 points in the race.

— This post was updated at 5:55 p.m.