Cynthia Nixon is left feeling inspired and has promised to "keep fighting" after she failed in her bid to become the governor of New York.
The former Sex And The City actress – who played Miranda Hobbes on the US show – was defeated by the incumbent Andrew Cuomo, who won the Democratic Party nomination for a third term.
In the weeks leading up to the vote, Mr Cuomo held a commanding lead in the polls and Nixon was unable to spring an upset in Thursday’s primary.
Nixon, who was hoping to cross the well-trodden path between showbusiness and political office, had run on a progressive platform to the left of Mr Cuomo.
Her policies included legalising marijuana and abolishing ICE, a federal body in charge of identifying and removing undocumented immigrants throughout the US.
In a series of tweets following her defeat, Nixon struck a defiant tone and urged her supporters to "change America".
She wrote: "This is an incredible moment for progressives, but it’s not just a moment — it’s a movement, and this movement is only growing stronger.
"Our numbers show that the younger you are, the more likely it is that you voted for me today. I’m particularly proud of that fact, and it gives me so much hope for the future of our party and our country.
"The generation coming of age in Obama and Trump’s America is one of the most progressive generations in history.
"You are going to change America — and for the first time in our history create a nation that finally belongs to all of us.
"This is not a time to settle for the way things are, or sit back and hope for things to change. This is a time to fight. As long as New York remains the single most unequal state in the country, we will keep fighting."
Nixon said her policies of legalising marijuana and improving the New York City subway system had forced Mr Cuomo, whose campaign boasted far superior financial resources, to react with similar promises.
She warned the Democratic Party it must "stand for something", if it is make gains in November’s mid-term elections and damage the presidency of Donald Trump.
Nixon added: "Thank you all for believing and fighting and leaving it all on the field. We started something here in New York, and it doesn’t end today. This is just the beginning. And I know that together, we will win this fight."
Mr Cuomo, 60, will face Republican candidate Marc Molinaro and independent Stephanie Miner during November’s election.