Peter Daou and James Boyce accused in the lawsuit, which to be filed in New York State Supreme Court in Manhattan, that Arianna Huffington and her partner Ken Lerer designed the website from a plan they had presented them.
US political journal Politico reported that Boyce and Daou charged that by stealing their idea, Huffington violated a handshake agreement to work together.
"Arianna Huffington and Ken Lerer presented the 'new media' ideas and plans of Peter Daou and James Boyce as their own in order to raise money for the website and enhance their image, and breached their promises to work with Peter and James to develop the site together," said the complaint.
However, Huffington and Lerer have rejected the charge of stolen ideas and broken deals. They described it as "a completely absurd, ludicrous supposition."
They also revealed in a written statement that Boyce and Daou have "tried to cash in" before filing the suit.
"For months now they have been trying to extract money from us. They are filing the lawsuit of course because we did not agree to any payment," they said in the statement.