The heart of the 26-page Iowa report blames the D.N.C. for the delay in results on caucus night. It states that the national party, weeks before the Feb. 3 caucuses, demanded a new tool to give it real-time results. This new tool, the report states, included coding errors that delivered inaccurate results, leading to a days-long delay before former Mayor Pete Buttigieg of South Bend, Ind., and Senator Bernie Sanders of Vermont finished in a virtual tie for first place.

“When the D.N.C.’s database conversion tool failed to work correctly, it caused the D.N.C. to wrongly stop the I.D.P. from reporting its results, and the I.D.P.’s entire planned reporting process was thrown into disarray,” the report says. “If the D.N.C. had not interjected itself into the results reporting process based on its erroneous data conversion, caucus night could conceivably have proceeded according to the I.D.P.’s initial plan.”

Iowa’s first-in-the-nation status was in jeopardy even before the 2020 disaster.