By Alina Selyukh
WASHINGTON, Aug 5 (Reuters) - U.S. Republicans are threatening to boycott 2016 presidential debates sponsored by networks CNN and NBC unless the networks cancel plans for special programs on Democrat Hillary Clinton, a possible 2016 White House contender.
In letters Monday to executives for NBC Entertainment and CNN Worldwide, Republican National Committee Chairman Reince Priebus said the programs amounted to political ads for Clinton, whose long public life has included serving as first lady, U.S. senator from New York and, most recently, secretary of state.
Priebus asked the companies to scrap plans by Aug. 14 for the CNN documentary film, due to premiere next year, and the NBC miniseries on Clinton, expected to air in 2015.
"As an American company, you have every right to air programming of your choice," Priebus wrote to NBC Entertainment Chairman Robert Greenblatt and CNN Worldwide President Jeff Zucker.
"But as American citizens, certainly you recognize why many are astounded at your actions, which appear to be a major network's thinly veiled attempt at putting a thumb on the scales of the 2016 presidential election."
Priebus said if CNN and NBC went ahead with the Clinton shows, he would seek a binding RNC vote that the Republican Party would not work with the two networks on its 2016 primary debates or sanction the debates sponsored by them.
State Republican Party leaders from Florida, South Carolina, New Hampshire, Nevada and Iowa followed up on Priebus's statement on Twitter, promising to support such a vote.
"Such political favoritism has no place in American journalism," said South Carolina Republican Chairman Matt Moore.
CNN called the Republican actions premature, given the non-fiction film is months away from completion.
"We would encourage the members of the Republican National Committee to reserve judgment until they know more," said CNN spokeswoman Barbara Levin. The documentary, commissioned by CNN's film unit, was expected to appear in theaters in 2014.
"Should they decide not to participate in debates on CNN, we would find it curious, as limiting their debate participation seems to be the ultimate disservice to voters."
An NBC spokeswoman said NBC News was completely independent of NBC Entertainment and had no involvement in the miniseries. NBC Entertainment declined to comment.
NBC's Greenblatt, when asked in July about Clinton's opponents potentially demanding equal time from the TV network, said NBC's series would likely air before the presidential race heats up in the spring or summer of 2015.
U.S. election laws require broadcasters to give equal access to free air time to legally qualified political candidates. The rules do not apply to news coverage.
Clinton, who lost the 2008 Democratic presidential nomination to President Barack Obama, has not said she is running in 2016 but many political analysts expect she will.