John Burton made the remarks Monday during a state delegation breakfast, in Charlotte, N.C., listing statements Ryan made during his acceptance speech at the GOP convention that numerous fact-checking organizations have concluded are inaccurate or misleading.
"They lie and they don't care if people think they lie," Burton said in comments posted online by KCBS-AM, Los Angeles. "Joseph Goebbels. The big lie, you keep repeating it."
The reference to Goebbels and Nazi propaganda techniques drew immediate outrage, The Sacramento Bee reported.
The Republican Jewish Coalition condemned Burton's remarks, the California Republican Party referred to them as "desperate" and "deranged" in a statement, and the Romney campaign issued a statement from former U.S. Senator Norm Coleman of Minnesota, who said in part, "All people of good will should repudiate such disgraceful words."
Burton -- who the Bee said has a reputation in Sacramento for making outrageous and profane comments -- offered what the newspaper called a tepid apology to the Romney campaign and "anyone who might have been offended by that comment."
He returned to California Tuesday for a previously scheduled dental procedure, the state party announced, and was not expected to return to the convention.