The US television network, NBC, has received criticism after it was revealed that it blocked advocates of equal marriage from using a pro-equality advert featuring the former First-Daughter.

Chelsea Clinton, the only daughter of Bill and Hillary Clinton, had recorded two political adverts showing her support for equal marriage, which were ready to be broadcast, however NBC News, her employer, wouldn’t allow the adverts to be shown because of her contract, reported Buzzfeed.

Sources aware of the adverts said that Ms Clinton featured in two ads, one aimed at Washington voters, and the other for a different group, but that NBC, where she had worked as a special correspondent since November 2011 “scuttled” the campaign.

Three people confirmed that they had seen the adverts, according to Buzzfeed, which reported:

“In the video, a third source said that Clinton described her belief that everyone should have the freedom to marry, detailed the importance of the upcoming votes, and stated that success in the states voting on marriage would send a message to rest of the country.”

Critics put an emphasis on how close the equal marriage polls were in Maine, Maryland, and Washington in the weeks leading up to the vote, and some have said that the support of such adverts could have proven anĀ invaluableĀ asset to equal rights advocates.

It is believed that the adverts were intended to be shown online, rather than on television, and one of the videos had been intended for TheFour2012.com

One of the founders of TheFour, Brian Ellner, said on the role the website, which featured a lot of celebrity endorsements including Jay-Z and Bruce Springsteen, had played in the time leading up to the ballots:

“In the days leading up to the election, we reached over 4 million unique visitors and over 3.2 million potential voters in The four states, including in top cities Baltimore, Seattle, and Minneapolis. On Election Day, we reached 2,237,203 people on Twitter alone.”

A long time advocate of equal marriage, Ms Clinton, spoke at a New York benefit last year, and urged straight people to join the fight for equal marriage rights.

Some have speculated that she is aiming for a political career, particularly given her increasingly vocal support of equal marriage.