A second attendee, requesting anonymity to discuss private conversations, said Sen. Ben Sasse of Nebraska was one name mentioned as a possible late entry contender who conservatives could rally around.

A spokesman for Sasse said he did not send a representative to the meeting.

Per three people familiar with the talks, the mood of the room was muted and downbeat. Attendees voiced frustration with the lack of coordination so far and wondered aloud whether Trump could be halted. The third-party scenario drew intense interest, but it also acknowledge that it would logistically and financially difficult with few major politicians willing for now to agree to take the political risk that such a run would entail.

Instead, a consensus emerged by the end that the best option may be working in upcoming primaries to boost Cruz and hope to prevent Trump from securing a majority of delegates and making a convention stand-off the culmination of those efforts, the people said.