Nancy Mace

Nancy Mace says she knew pursuing the infamous Epstein Files could cost her in the next election ... but she had to try anyway.

The congresswoman took to X on Friday to acknowledge President Donald Trump endorsed her opponent, Lt. Gov. Pamela Evette in the South Carolina gubernatorial race ... and, while he's not in her corner, she didn't go directly after POTUS.

She says she has tremendous respect for Trump ... but adds the state and system is corrupt -- and his choice for governor is part of that corruption.

Mace goes on to say she will "drain the swamp" -- a popular line from President Trump's 2016 presidential campaign -- willingly standing up against both political parties for the good of South Carolinans.

Then, Mace gets into Epstein ... writing, "I also know I put the likelihood of an endorsement on the line when I demanded transparency on the Epstein files. I demanded it because you deserved the truth - ALL OF IT - and as a survivor, I had to get justice for these women. If this is the price of an endorsement, I will never pay it."

Again, she doesn't invoke Trump's name specifically, but her meaning is clear ... she went after the Epstein files -- and it cost her his support. She shared a pic of herself and Trump grinning as well ... with "MAGA MACE" written across the bottom.

ICYMI ... Trump endorsed Lt. Gov. Evette on Truth Social Friday -- hours after Mace told people there's no way he would endorse her competition.