House Republican Leader McCarthy needs 218 votes from the Republican-majority House to be elected speaker, but he fell short of two votes late on Friday night.
The House is voting whether to hold a 15th vote late Friday night into early Saturday morning or adjourn until Monday.
Republicans are considering a $75 billion cut to US defense spending as part of the effort to rally support behind McCarthy, although some defense hawks who have so far voted for McCarthy expressed concerns about the proposal, US media reported on Friday.
The situation marks the first time in a century the House has failed to elect a speaker on the first ballot, and the first time since 1859 it has taken more than ten ballots.