And as recently as the past 48 hours, Romney has told associates in at least two of the GOP campaigns that he has no plan to endorse before New Hampshire votes.

But close Romney allies do not rule out a last minute change of heart. In saying that, they acknowledge a shift in his thinking about the race post-Iowa, and these sources tell CNN that should Romney decide to drop his neutrality before Tuesday, the all-but-certain recipient of that blessing would be Marco Rubio.

CNN is told there is a fresh Rubio effort to win Romney’s endorsement based on his third place showing in Iowa. The Florida senator’s team makes the case that now is the time to coalesce around Rubio as the strongest alternative to Trump and Texas Sen. Ted Cruz…

Romney, according to sources close to the former Massachusetts governor, has a trademark reaction to such talk: Is there data to support the argument that Rubio is in play to defeat Trump in New Hampshire?

In short: Is there evidence to persuade Romney it is worth getting involved now — a decision that would put his personal prestige on the line and disappoint his other friends in the field?