Underdeliver

[…] the result was a warning to all exhibition organisers about the dangers of overpromising and underdelivering when promoting events.

Hope Hicks, one of the President’s longest-serving aides, warned Parscale against touting ticket request numbers, reminding him that the number one rule in politics is not to overpromise and underdeliver, a source familiar with the matter said.

"[...] If the economy has tanked... then we don't want to over-promise and under-deliver."