with all due respect

Although I think highly of you, as in With all due respect, you haven't really answered my question, or With all due respect, that account doesn't fit the facts. This phrase always precedes a polite disagreement with what a person has said or brings up a controversial point. [c. 1800]

The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.