The chairman of the Senate Judiciary Committee is upending longstanding precedent on two judicial nominees.

Republican Sen. Chuck Grassley of Iowa said Thursday he's going ahead with confirmation hearings for two appellate court nominees, David Stras of Minnesota and Kyle Duncan of Louisiana, even though they have not received the support of both of their home-state senators.

In each case, a senator declined to return a so-called blue slip marking their support for the judicial nominee from their state. Grassley said he won't allow a single senator to block a nominee. Rather, he said a negative blue slip will only be considered a significant factor for the committee to weigh when evaluating a nominee.

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"This practice is consistent with the vast majority of the blue slip's history," Grassley said.

When President Barack Obama was in office, Republicans blocked scores of judicial nominees by declining to return a blue slip. That tool was one of the few Democratic lawmakers had available to them in trying to stop some of President Trump's nominations.

Sen. Dianne Feinstein, the ranking Democratic senator on the Judiciary Committee, said Grassley's decision couldn't be more troubling.

"The lengths to which Republicans are going to jam extremely conservative and controversial nominees through the Senate is unprecedented," Feinstein said. "What's happening is diminishing the Judiciary Committee and the Senate and undermining the independence of the federal judiciary."

On the committee's website, Republicans said that only two chairmen over the past century adopted a policy requiring two positive blue slips as a prerequisite for committee consideration of a judicial nominee. Sen. Patrick Leahy, D-Vt., had that policy when he ran the committee for eight years until 2015.

Feinstein said that Grassley followed that precedent when he became chairman and when Obama was president.

"There's a long history as it pertains to the blue slip, but what's most relevant is the last two years," Feinstein said. "Republicans shouldn't have one blue slip policy for Democratic presidents and another for Republican presidents.

"In 2015 and 2016, Chairman Grassley refused to allow multiple nominees of President Obama's to have hearings because they didn't have two blue slips from home-state senators."

Senate Majority Leader Mitch McConnell, facing pressure from conservative groups, said last month that he was seeking to upend the blue slip tradition for circuit judges. He described it as "simply a notification of how you're going to vote, not a blackball."

Grassley said he will be less likely to proceed when a district court nominee fails to have two positive blue slips from home-state senators.

"But circuit courts cover multiple states," Grassley said. "There's less reason to defer to the views of a single state's senator for such nominees."