Judge Andrew Napolitano said Wednesday that after Justice Anthony Kennedy retires from the Supreme Court at the end of July, the key issue facing the court will be abortion.

Kennedy, 81, informed the White House of his plans Wednesday in a letter after 30 years of service.

Napolitano said on "The Daily Briefing with Dana Perino" that Kennedy has been the swing vote in hot-button cases.

He said that although Kennedy is Roman-Catholic and was appointed by Ronald Reagan, he's consistently sided with liberals on the topic of abortion.

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Kennedy's retirement could give President Trump the opportunity to move the court solidly to the right.

Napolitano added Wednesday that if Trump nominates a pro-life nominee, there will be a "titanic" battle throughout the Senate, as it would create a pro-life majority on the Supreme Court for the first time since the Roe v. Wade decision in 1973.

A vacancy on the court is sure to become a key issue during the midterm elections in November. 

Napolitano said that after Justice Neil Gorsuch was confirmed last year, Trump added three names to a list of potential justices who have track records of keeping the government "within the confines of the Constitution"

Napolitano also relayed a conversation that he had with the late Justice Antonin Scalia, who told him that Kennedy once said he would not retire until a Republican president took office and there was a Republican majority in the Senate

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