Ronald Reagan is not the author of the 11th Commandment embedded in the philosophical lore of the Republican Party.

But he is its personification.

The dictum “Thou shall not speak ill of any fellow Republican” was contrived in 1966 by the leader of California’s Republican Party, Gaylord Parkinson, who sought to end internecine warfare dividing the GOP and costing it elections.

That year, in the gubernatorial primary, Reagan was enduring a verbal battering by fellow party member George Christopher. With the arrival of the 11th Commandment, the carping stopped. Reagan surged into the governor’s seat.

Adherence is now nationwide. Republicans recognize a divided party is often a defeated one, and view this policy of campaigning as not only a rhetorical girdle for party unity but also an instrument of behavior modification for candidates.

In Washington state, some Republicans are concerned that it’s become a weapon of coercion and deterrence against undesired candidates. Nowhere is enforcement done with more muscle and threat than here.

This state’s Republican Party demands that Republican candidates in a primary sign an agreement pledging they will not “attack or defame an opponent by name or innuendo” and will “disavow” mailers and phone calls that do the same. They also agree to publicly endorse the primary winner.

Not signing results in near ex-communication; the candidates don’t receive an ounce of support or a dime of data from the party.

This made headlines in last year’s U.S. Senate primary between Reed Davis, former King County Republican Party chairman, and U.S. Rep. George Nethercutt.

Davis, a heavy underdog, would not sign because it would have meant halting his unbending criticism of Nethercutt’s service and record. The penalty: Davis was barred from addressing delegates at the party’s state convention.

But Washington goes even further. Candidates who sign the loyalty oath then break it face a $5,000 fine from the party.

It’s never been imposed, but the threat scares off some candidates from signing.

“It just sounds like a bad policy,” said David Mark, editor in chief of Campaigns and Elections magazine, which covers candidates, their strategies and their conduct.

There is an obvious problem of enforcement. Who decides the line between speaking critically and speaking ill of one’s opponent, and thus what is a violation.

In the crazy kinetics of campaigns, attacks are often launched by groups that support a candidate but are independent of that person’s control. It can cause a riptide effect.

State GOP leaders realize changes may be needed. They’ve appointed a committee, including Snohomish County Republican Party Chairman Steve Neighbors, to bring recommendations.

The panel may do away with the fines. It might try to spell out what it means to “speak ill.” Everything is on the table, except erasing the commandment.

“The point of all of this,” said Everett Republican activist Frauna Hogland, “is to be sure the candidates attack the Democratic opponent, not the Republican opponent.”

Reporter Jerry Cornfield’s column on politics runs every Sunday. Reach him at 360-352-8623 or jcornfield@heraldnet.com.