Senate Judiciary Committee chair Chuck Grassley says that if he's still chairman in 2020, the Senate will not move to fill any potential vacancy on the United States Supreme Court. Grassley, in an interview with Fox News' Martha MacCallum on Tuesday, said he'd adhere to a "pledge" he made back in 2016 during the stalled confirmation process of Judge Merrick Garland to the Supreme Court.

"If I'm chairman, they won't take it [Supreme Court nomination] up," said Grassley. "No, because I pledged that in 2016." He added however that if someone else were to take over the role of committee chair, "they'll have to decide for themselves, but that's a decision I made a long time ago."

After Sen. Orrin Hatch, R-Utah, retires at the end of the year, Grassley may become the Finance Committee chairman. Grassley's potential successor on the Judiciary Committee, the Washington Post pointed out, is GOP Sen. Lindsey Graham of South Carolina -- who has said the Senate would wait for the presidential election to take place before filling another opening on the bench.

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"If an opening comes in the last year of President Trump's term, and the primary process has started, we'll wait until the next election," Graham said in remarks at the Atlantic Festival last week.

Grassley's comments contrast with those of Senate Majority Leader Mitch McConnell, who may be more open to filling a vacancy during a presidential election year, telling "Fox News Sunday's" Chris Wallace, "We'll see if there's a vacancy in 2020."

McConnell on Monday argued that if control of the White House and the Senate had been reversed in 2016, Democrats wouldn't have filled a vacancy either.

"Everybody just smiled because they knew if it had been a Republican president and a Democratic Senate, they wouldn't have filled a vacancy," he said.

Grassley added that should the balance of power shift to Democratic control of the House and Senate in the upcoming midterm elections, Democrats moving to impeach Justice Brett Kavanaugh from his role on the court was not a "wise thing to do."

"There's no basis for impeaching but, all this talk prior to Saturday's vote or since Saturday's vote, every effort made in the last month has been to detract from his [Kavanaugh's] outstanding qualifications," said Grassley.