by Mark Silva

First the writers silenced Jay Leno and David Letterman.

Now the writers may silence Hillary Clinton, Barack Obama, John Edwards and company.

In the case of the late-night comics, it's the Hollywood writers' strike that has cast the television entertainment world into reruns.

In the case of the Democratic candidates for president, it's the threat of a news-writers' strike that could imperil the final party debate before the Iowa caucuses on Jan. 3.

The Democrats today pledged not to cross the picket line, if CBS News writers strike before the planned Dec. 10 Democratic debate in California, the last in a long-running series of debates before the first presidential nominating caucuses in January.

Sen. Hillary Clinton (D-N.Y.) issued a statement about the Los Angeles debate that CBS plans in conjunction with the Democratic National Committe: "“It is my hope that both sides will reach an agreement that results in a secure contract for the workers at CBS News, but let me be clear: I will honor the picket line if the workers at CBS News decide to strike,''\

Former Sen. John Edwards of North Carolina made the same pledge in a conference call with reporters. And spokesmen for Sen. Barack Obama of Illinois, Gov. Bill Richardson of New Mexico and Sen. Chris Dodd of Connecticut said they too will not participate in that debate.

CBS News writers this week authorized their union leaders to call a national strike. About 500 of the network’s TV and radio news writers in New York, Los Angeles and other cities have been working under an expired contract since April 2005. CBS News called the vote “unfortunate” and said its latest offer was “fair and reasonable.”

“The Democratic Party believes the right to organize and collectively bargain is one of our most fundamental rights, and we are proud to stand with the working men and women in the labor movement,” DNC spokeswoman Karen Finney said. “Given the Democratic Party’s long history of supporting the labor movement in America, if the strike is still going on, we will not cross the picket lines.”