2020 Democratic presidential candidates are silent about whether they support recent progressive calls to "pack" the Supreme Court over anger with the conservative majority.

Asked by the Washington Free Beacon if they would consider adding more Supreme Court justices upon becoming president, officially declared 2020 candidates Sen. Elizabeth Warren (D., Mass.), Sen. Bernie Sanders (I., Vt.), Sen. Kamala Harris (D., Calif.), Sen. Cory Booker (D., N.J.), Sen. Amy Klobuchar (D., Minn.), former Colorado Gov. John Hickenlooper (D.), Washington Gov. Jay Inslee (D.), Rep. Tulsi Gabbard (D., Hawaii) and former Obama housing chief Julián Castro did not respond.

Sen. Kirsten Gillibrand (D., N.Y.). who's formed an exploratory committee, also did not respond, although she's previously called the notions of court-packing or imposing term limits "interesting ideas" that she would have to think more about.

Former Attorney General Eric Holder said last week the next Democratic U.S. president should consider adding seats to the Supreme Court upon taking office. Democrats are still fuming over Senate Republicans' denial of a hearing and vote for Merrick Garland, the judge nominated in 2016 by President Barack Obama after the death of Justice Antonin Scalia.

While Article III of the Constitution does not specify the number of judges on the Supreme Court, the Judiciary Act of 1869 is the most recent legislation to establish the size as one chief justice and eight associate justices.

"Given the Merrick Garland situation, the question of legitimacy is one that I think we should talk about," Holder told the Washington Post. "We should be talking even about expanding the number of people who serve on the Supreme Court, if there is a Democratic president and a Congress that would do that."

The idea has gained momentum on the left with the formation of the group named "Pack the Courts." It's working with another liberal organization, "Demand Justice," to try to push Democrats to expand the Supreme Court's size. Demand Justice director Brian Fallon, Hillary Clinton's former press secretary, is an enthusiastic proponent of the idea. The group he leads was formed to fight Trump's judicial nominees.

"At Demand Justice, we strongly believe that reforming the court—especially by expanding it—is the cornerstone for re-building American democracy," he told Politico. "The Kavanaugh court is a partisan operation, and democracy simply cannot function when stolen courts operate as political shills."

Fallon did not respond to a Free Beacon request for comment.

South Bend, Indiana Mayor Pete Buttigieg, who has formed a presidential exploratory committee, is the only candidate to express any enthusiasm for the idea.

"I don’t think we should be laughing at it," he said last month. "Because in some ways, it’s no more a shattering of norms than what’s already been done to get the judiciary to where it is today."

Rep. Eric Swalwell (D., Calif.), who is considering getting into the race, told Fox News last month he wouldn't consider such a proposal, saying "nine is a good number."

2020 Watch: Likely Democratic presidential contender @RepSwalwell – asked in NH if he would consider 'packing' the #SupremeCourt if elected to the White House, tells @foxnewspolitics "I wouldn’t. I think nine is good number." #nhpolitics #FITN #2020Election #CApolitics pic.twitter.com/VcOF74sGPS — Paul Steinhauser (@steinhauserNH1) February 25, 2019

President Donald Trump has had two Supreme Court justices confirmed during his administration: Neil Gorsuch and Brett Kavanaugh. Gorsuch filled the seat left open by Scalia's death, and Kavanaugh replaced Anthony Kennedy, who retired last year. Of the nine current judges, five were nominated by Republican presidents: Gorsuch, Kavanaugh, Chief Justice John Roberts (George W. Bush), Justice Samuel Alito (Bush) and Justice Clarence Thomas (George H. W. Bush).

Trump campaigned on promising to nominate conservative judges and even produced a list of potential names for voters to consult. Senate Majority Leader Mitch McConnell (R., Ky.) has made confirming the White House's judicial nominees a top priority.

Coming off a dominating re-election victory in 1936, Democratic President Franklin D. Roosevelt tried to pack the Supreme Court the following year via the passage of the Judicial Procedures Reform Bill. It would have allowed him to nominate a new justice for every judge over the age of 70 years, six months, who didn't retire.

His plan would have expanded the court to as many as 15 justices as he sought judges more supportive of the "New Deal," but it was criticized as an authoritarian power grab and ultimately failed.