(CNN) President Donald Trump's attorney plans to appeal a New York Supreme Court judge's decision to allow a defamation lawsuit against the President to go forward.

The suit was filed by former "Apprentice" contestant Summer Zervos in January 2017 and alleges Trump defamed her after she accused him in an October 2016 news conference of sexually assaulting her in 2007.

"We disagree with this decision, which is wrong as a matter of constitutional law," said Marc Kasowitz, who is representing Trump in the case. "We intend to immediately appeal and will seek a stay of the case until this issue is finally determined."

The decision by New York Supreme Court Judge Jennifer Schecter is a significant development for a President already facing a lawsuit by an adult film star who was paid to keep quiet about her allegations of a consensual affair with Trump. It could also open the floodgates for similar cases focused not on the misconduct itself, but on Trump's response to the allegations. Trump's personal lawyer Michael Cohen said in a statement that Trump "vehemently denies" any encounter with porn star Stormy Daniels.

Zervos says Trump kissed her twice on the lips during a lunch meeting in his New York City office, and alleges he kissed her aggressively and touched her breast on a separate occasion in Beverly Hills.

Trump has repeatedly denied Zervos' claims.

On the same day that Zervos held a news conference to make her allegations public, Trump responded in a statement that was widely reported and appeared on his campaign website, "To be clear, I never met her at a hotel or greeted her inappropriately a decade ago. That is not who I am as a person and it is not how I've conducted my life."

He repeated his denials in campaign rallies and at presidential debates and even re-tweeted a tweet that included a picture of Zervos and the words, "This is all yet another hoax."

Trump's lawyers had filed a motion to dismiss the case, arguing during a December 2017 hearing that a President has immunity from such lawsuits in state courts and that the case would conflict with his official duties, arguments Schecter dismissed. The team also tried to argue the President's frequent denials of accusations made by Zervos and others were protected political speech as statements of opinion.

But Schecter ruled, "defendant's repeated statements -- which were not made through op-ed pieces or letters to the editor but rather were delivered in speeches, debates and through Twitter, a preferred means of communication often used by the defendant -- cannot be characterized simply as opinion, heated rhetoric or hyperbole," she said. "That defendant's statements about plaintiff's veracity were made while he was campaigning to become President of the United States, does not make them any less actionable."

Tuesday's ruling cites the 1997 Clinton vs. Jones sexual harassment lawsuit, in which the US Supreme Court held that a sitting president is not immune from being sued in federal court for unofficial acts.

That case left open the question of whether "concerns of federalism and comity compel a different conclusion for suits brought in state court." Schecter ruled such concerns do not prevent this case from moving forward.

"No one is above the law," she wrote. "It is settled that the President of the United States has no immunity and is 'subject to the laws' for purely private acts."

The lawsuit could have huge ramifications for Trump, who could possibly be deposed in the case and potentially called on to testify. Zervos' legal team subpoenaed Trump's campaign in March of 2017 for all documents relating to her, all communications with or about her and "all documents concerning any woman who asserted that Donald J. Trump touched her inappropriately." The subpoena was served to the campaign, but the two legal teams agreed to suspend the response date until after the motion to dismiss the lawsuit was decided.

Zervos is one of more than a dozen women who have accused Trump of sexual misconduct ranging from groping of their buttocks and genitalia to unwanted kissing. He has also been accused by two additional women of inappropriate behavior like ogling. Trump's team has denied all of the allegations.