The group that met with McCarthy on Thursday was about one-quarter of the full House Freedom Caucus' roughly 40 lawmaker membership, but it included influential founding members Reps. Jim Jordan of Ohio; Raul Labrador of Idaho; Justin Amash of Michigan; and Mick Mulvaney of South Carolina.
The lawmakers were inside for about 45 minutes and left together, declining to speak about how it went inside, calling it a private meeting.
Especially in the wake of comments criticized for politicizing the work of the Select Committee on Benghazi, McCarthy can't afford to lose many members' support in order to avoid an embarrassing round of multiple speaker votes or needing Democrats.
The gathering one of a handful of meetings lined up for leadership candidates to court their conservative colleagues. On Wednesday night, Jordan told CNN that next Tuesday evening, the Freedom Caucus, Liberty Caucus and a few other constituencies will hold a forum with candidates for leadership positions.
On Wednesday night, the larger Republican Study Committee will hold its own forum, ahead of the Thursday conference leadership vote.
McCarthy is seeking to lock up support in his bid for speaker. He needs a majority of Republicans to vote for him as the nominee when the conference votes next Thursday -- but he needs 218 votes when the entire House votes on the speakership after Boehner leaves his post at the end of October.
To get 218, McCarthy can only lose 29 Republican votes on the floor, assuming Democrats vote for Minority Leader Nancy Pelosi, as custom.
The Freedom Caucus has been a thorn in Boehner's side. The right flank of the GOP has consistently challenged his speakership, and their opposition was a large factor in his decision to resign at the end of the month.
Currently, McCarthy's only challenger is Florida Rep. Daniel Webster, who only got 12 votes when he challenged Boehner in January.
Later, Amash told CNN the meeting was cordial, but that his support wasn't yet behind McCarthy. Amash said "there's not a lot of evidence" things will change if leaders just move up one spot following the Boehner resignation.
The Freedom Caucus' rules require that 80% of the members agree on a strategy before it becomes a formal caucus position -- meaning McCarthy would need to convince that percentage of the members to support him to guarantee unanimous backing. Otherwise, they'd vote individually.
McCarthy has been engaging in steady outreach with the members, beginning his phone calls to them immediately after Boehner announced his resignation
Separately on Thursday morning, at the same time as the Freedom Caucus meeting, the Pennsylvania delegation was interviewing candidates for majority whip in the Majority Leader's Office, as well. McCarthy was not involved in that meeting.
McCarthy's office did not comment on the meeting and McCarthy avoided reporters around the Capitol on Thursday.