On Thursday, Biden told reporters that revealing it now would distract voters from focusing on Trump's nomination of Amy Coney Barrett to the top court.
The feud over the appointment of a Supreme Court justice is reminiscent of when, in 2016, Justice Antonin Scalia died in February, and the Republican-dominated senate refused to hold hearings for (Democratic) President Barack Obama's nominee, Merrick Garland, who was nominated 237 days before the election. Roosevelt proposed to pack the Court in the 1930s, when several conservative justices were inclined to declare parts of his program, the New Deal, unconstitutional. "That's the answer to the question".
But the Democratic ticket has made a decision to draw a red line on taking a position on court-packing, guaranteeing that Mr. Biden and Ms. Harris will get asked about it continually over the next month. Donald Trump has nominated Amy Coney Barrett to the Supreme Court.
"We should leave all options on the table, including the number of justices that are on the Supreme Court", Representative Alexandria Ocasio-Cortez said earlier in September.
The Supreme Court issue has become acute in the presidential race, after the passing of Justice Ruth Bader Ginsburg, opening a vacancy in the Court - one that Trump is eager to fill. Republican Party has said that it will push for confiemation from the Senate before November 3 election.
Some in the GOP slammed an idea they claim would undermine democracy and "destroy the credibility of our nation's highest court".