Sen. Susan Collins Susan Margaret CollinsGraham: GOP will confirm Trump's Supreme Court nominee before the election Gardner signals support for taking up Supreme Court nominee this year Tumultuous court battle upends fight for Senate MORE (R-Maine) was caught on a hot mic Tuesday talking about the looks of GOP Rep. Blake Farenthold Randolph (Blake) Blake FarentholdThe biggest political upsets of the decade Members spar over sexual harassment training deadline Female Dems see double standard in Klobuchar accusations MORE (Texas), who a day earlier was quoted in a story blaming “some female senators from the Northeast” for the healthcare repeal impasse.

“Did you see the one who challenged me to a duel?” Collins asked Sen. Jack Reed John (Jack) Francis ReedWhen 'Buy American' and common sense collide Hillicon Valley: Russia 'amplifying' concerns around mail-in voting to undermine election | Facebook and Twitter take steps to limit Trump remarks on voting | Facebook to block political ads ahead of election Top Democrats press Trump to sanction Russian individuals over 2020 election interference efforts MORE (D-R.I.) following a spending bill markup.

“Trust me, you know why he challenged you to a duel? Because you could beat the shit out of him,” Reed says.

Collins called Farenthold "huge," then brought up a picture of him that was taken at a fundraiser while he was wearing duck-print pajamas and standing next to a lingerie model.

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“He’s so unattractive, it’s unbelievable,” Collins says. “Did you see the picture of him in his pajamas next to this bunny, playboy bunny?”

Farenthold was quoted in a local radio interview on Friday as saying that he would be willing to challenge a lawmaker holding up ObamaCare repeal to a duel.

The House lawmaker said that “if it was a guy from south Texas, I might ask him to step outside and settle this Aaron Burr-style.”

Collins later apologized to her Republican colleague in a statement a spokesman provided to CNN.

"Neither weapons nor inappropriate words are the right way to resolve legislative disputes," Collins said. "I received a handwritten apology from Rep. Farenthold late this morning. I accept his apology, and I offer him mine."

Tensions have been boiling over as the Senate has been struggling to repeal and replace ObamaCare. The chamber delayed its August recess in an effort to get legislation over the finish line before lawmakers leave town.

Collins has been one of the most vocal critics of the Senate's healthcare bill, citing concerns over deep cuts to Medicaid. She was one of only two Republicans to vote against a Tuesday motion to proceed to debate on the chamber's latest effort to uproot ObamaCare.

—Updated at 4:56 p.m.