Republicans have called on two US TV networks to drop plans for programmes about former Secretary of State Hillary Clinton, calling them unfair promotion.
Republican National Committee Chairman Reince Priebus told NBC and CNN the shows would put a "thumb on the scales" of the 2016 presidential election.
He also warned Republicans could refuse to hold debates on the two networks.
The Democrat has not said if she will run for president, though analysts say she would lead the early field.
Mrs Clinton, wife of former President Bill Clinton, has been closely watched as a possible contender for the Democratic Party's 2016 nomination since leaving her position as secretary of state under President Barack Obama in January.
Capitalising on her popularity, CNN has announced plans for a feature-length film about the former first lady with Academy Award-wining director Charles Ferguson. It is scheduled to air in 2014.
Also, broadcaster NBC is in the early stages of producing a miniseries about Mrs Clinton starring actress Diane Lane.
On Monday Mr Priebus, who is chairman of the Republican National Committee but is not an elected official, said it was "disturbing and disappointing" that the channels would seek to "promote" Mrs Clinton.
"It's appalling to know executives at major networks like NBC and CNN, who have donated to Democrats and Hillary Clinton, have taken it upon themselves to be Hillary Clinton's campaign operatives," he said.
Mr Priebus also warned that if the networks did not agree to cancel the productions by the end of summer, he would ask the Republican National Committee to refuse to hold primary election debates on the networks.
The networks declined to comment on the Republican National Committee's letters.