A Republican politician has blamed "female senators" for the spluttering efforts by his party to pass a healthcare bill.
Blake Farenthold, a congressman from Texas, told a local radio station if a man were responsible, he would challenge him to a duel.
Susan Collins of Maine was one of three female Republicans who said they could not back the Senate's healthcare plan.
The party has long vowed to replace President Barack Obama's signature law.
But there are deep divisions on what the Republican bill should contain.
On Monday, US President Donald Trump made a rare speech aimed at geeing up his party to make one more healthcare push.
What did President Trump say?
The president stood on a stage at the White House alongside people he said were "victims" of the way so-called Obamacare had wrecked the healthcare system.
"To every member of the Senate I say this: The American people have waited long enough. There's been enough talk, and no action. Now is the time for action."
In a very partisan 10-minute speech, he also blamed Democrats for "obstructing" the Republican effort, even though his party controls both chambers in Congress and the White House.
On Tuesday, there will be a vote in the Senate on whether to bring the bill to the floor for debate and a vote.
But if that procedural vote passes, it is not clear what kind of bill senators would then be considering.
Senator Ron Johnson told reporters: "I don't have a clue what we're going to be voting on."
What did the Texan congressman say?
In an interview with radio station 1440 Keys, Mr Farenthold appeared to point the finger at his own party.
"The fact that the Senate does not have the courage to do some things that every Republican in the Senate promised to do is just absolutely repugnant to me," he said.
He added: "Some of the people that are opposed to this, they're some female senators from the North East."
If it was "a guy from south Texas" who was generating so much discord in the party, he would ask them to settle their differences in a gun fight, he said.
There was an outcry when Republican Senate leader Mitch McConnell drafted the first healthcare bill in a group of 13 that did not include any women.
Who are the rebels?
There are concerns from moderate Republicans, Democrats and groups representing the health service that the Republican plan will strip millions of poor Americans of healthcare.
Ms Collins, a moderate Republican, has been strongly opposed to the Republican bill from the start over cuts to Medicaid, a government health programme for the poor.
Republican Senators Lisa Murkowski of Alaska and Shelly Moore Capito of West Virginia also came out against the bill, expressing concerns over plans to weaken protections for people with pre-existing conditions and affordability.
Mrs Capito was especially concerned with the cuts to Medicaid, which her state expanded under Obamacare.
All three female senators also emphasised they could not vote to repeal Obamacare without a replacement plan in place.
This is House anger - Anthony Zurcher, BBC News, Washington
Congressman Blake Farenthold isn't the kind of guy to hold his tongue. He's also no stranger to charges of misogyny, what with allegations of sexual harassment and being the subject of one of the most embarrassing pyjama photos in US political history.
Beneath the bluster from the South Texas Republican, however, is a bitter truth. Republicans in the House of Representatives are seething over the possibility that senators will hang them out to dry on healthcare reform.
After some drama, in May House Republicans voted in favour of unpopular healthcare legislation they were promised would be smoothed out in the Senate.
Democrats on the House floor took delight in a vote they believed would come back to haunt their counterparts in the 2018 congressional elections.
While that may be a reality for some moderate Republicans, they were buoyed by thoughts of fulfilling a long-time campaign promise and achieving a key conservative goal.
But what if that isn't the case? What if House Republicans took a hard vote and got nothing in return except the president's derision and months of Senate wheel-spinning?
They would be angry. And some, it seems, would eye their metaphorical duelling pistols.