With 11 failed attempts to win the job of House Speaker since Tuesday, it was not apparent that McCarthy had any path to nail down the majority needed to win the job.
In an 11th round of voting, the holdouts quickly amassed enough votes to deny McCarthy the job again before the House voted to adjourn until midday Friday.
With its inability to choose a leader, the 435-seat House has been rendered impotent - unable even to formally swear in newly elected members let alone hold hearings, consider legislation or scrutinise Democratic President Joe Biden and his administration.
Republicans won a slim 222-212 majority House majority in the November midterm elections, meaning McCarthy cannot afford to lose the support of more than four Republicans as Democrats united around their own candidate.
Not since 1923 had the House failed to elect a speaker on the first ballot.
That year, it took nine rounds of voting - a mark matched and later surpassed on Thursday.
McCarthy, a congressman from California who had served as the top House Republican since 2019 and was backed by former President Donald Trump for the post, offered the holdouts a range of concessions that would weaken the Speaker's role, which political allies warned would make the job even harder.
That failed to quell the revolt.
In several rounds of voting on Thursday, McCarthy won the support of 201 Republicans, short of the 218 votes needed to succeed Democrat Nancy Pelosi as Speaker.
Twenty Republicans voted for other candidates, including Trump, and a 21st declined to back any candidate.
The 9th, 10th and 11th rounds of voting saw the House pass a record that has stood since 1859 in the turbulent years preceding the US Civil War that ended slavery.
McCarthy's opponents remained unyielding, saying that they do not trust him to stick to the scorched-earth tactics they want to use against Biden and the Democratic-controlled Senate.
"This ends in one of two ways: either Kevin McCarthy withdraws from the race or we construct a straitjacket that he is unwilling to evade," said Republican Representative Matt Gaetz, who voted for Trump for Speaker.
As Speaker, McCarthy would hold a post that normally shapes the chamber's agenda and is second in the line of succession to the presidency behind Vice President Kamala Harris.
He would be empowered to frustrate Biden's legislative agenda and launch investigations into the president's family and administration in the run-up to the 2024 presidential election.
More than 200 Republicans have backed McCarthy in each of the votes this week, with less than 10 per cent of lawmakers in the party against him.
"I'm very worried about it and I'm on the intelligence committee," said Republican Representative Brian Fitzpatrick, a McCarthy supporter who said that he was unable to participate in classified briefings until a Speaker is chosen and he is sworn in.