President Donald Trump could have an easier time appointing conservative judges to California’s federal courts under a policy shift in the U.S. Senate this week that is drawing withering criticism from Sen. Dianne Feinstein.

Senate Judiciary Committee Chairman Chuck Grassley, R-Iowa, said Thursday that he wouldn’t necessarily follow the Senate’s informal “blue slip” policy, which allows senators to veto judicial nominees in their home states.

That means that Feinstein and fellow Democratic Sen. Kamala Harris won’t hold sway over nominees to California’s federal courts or Californians nominated to the Ninth Circuit Court of Appeals. Instead, the Republican majority in the Senate would be able to confirm Trump’s picks.

The blue slip tradition, which has been in place for more than a century, is one of the last tools Democrats have to stop Trump from shaping the federal judiciary with lifetime appointments. Ending the practice — which involves senators returning to the judiciary committee a literally blue slip of paper to say whether they approve of the nomination — would be the latest escalation in a years-long struggle between Republicans and Democrats over nominating and confirming federal judges.

Feinstein, the ranking Democrat on the Judiciary Committee, blasted Grassley’s decision, saying it would undermine the independence of federal judges.

“The lengths to which Republicans are going to jam extremely conservative and controversial nominees through the Senate is unprecedented,” she said in a statement. “There’s only one reason to eliminate the blue slip — and that’s to allow President Trump to completely cut Democrats out of the process of selecting judicial nominees and continue the pattern of selecting nominees far outside the mainstream.”

Under President Barack Obama, Republican senators were able to block more than a dozen judicial nominees from their home states. No Obama nominee got a nomination hearing without the support from both of their home state senators. And no nominee has been confirmed without two blue slips approving of the nomination from their home-state senators since 1989.

But Grassley and his allies argue that the process is being hijacked by Democratic senators to block even reasonable nominees for judgeships. In the two cases Grassley cited Thursday, involving judicial nominees in Minnesota and Louisiana, one senator from each state had returned a blue slip and the other senator had not. He suggested he would decide whether to honor blue slips on a case-by-case basis.

“The blue slip courtesy is just that — a courtesy,” Grassley said on the Senate floor Thursday.

Still, it’s a major policy change, said Carl Tobias, a law professor at the University of Richmond in Virginia who studies federal judicial nominations.

“The Senate works on the basis of tradition and courtesy and mutual self-respect,” Tobias said. “Now he’s overturning those traditions.”

Both parties have switched sides on the debate since the Obama administration. When they were in the majority in 2013, Democratic senators ended the filibuster for judicial nominees, saying a minority of Republican senators shouldn’t be able to veto Obama’s choices. In 2014, Republican Judiciary Chairman Orrin Hatch, R-Utah, wrote in an op-ed that “weakening or eliminating the blue slip process” would be “disastrous.”

Feinstein’s thinking on the issue has also changed. In a speech on the Senate floor in June 2001, she said that she “would move to abolish the blue slip” and that it was “just plain wrong” that a single senator could “stop a nomination dead in its tracks.”

In 2003, however, she opposed a Bush appeals court nominee from California and urged the Senate to uphold the blue slip tradition. The nominee, Carolyn Kuhl, was not confirmed.

Trump has moved swiftly over the last year to remake the federal judiciary, appointing conservative judges to federal district and appeals courts around the U.S. and taking advantage of large numbers of vacancies on the bench. But until now he hasn’t nominated any judges for California’s federal district courts — in part because opposition from Feinstein or Harris could have derailed a nominee’s chances.

Harris’ office didn’t respond to requests for comment on Friday.

There are currently seven vacancies in California’s federal district courts: six in the central district, which covers Los Angeles and much of the surrounding area, and one in the southern district, which covers San Diego and Imperial counties. There are also four open seats on the Ninth Circuit Court of Appeals, which includes California and most of the western U.S. — and which Trump said he wanted to break up after its justices ruled against a proposed travel ban earlier this year.

So far, Trump has nominated just a single judge for these vacancies: Ryan Bounds, an assistant U.S. attorney in Oregon, for a seat on the Ninth Circuit. Oregon’s two senators, Democrats Ron Wyden and Jeff Merkley, have both refused to return a blue slip, arguing that they weren’t consulted on Bounds’ nomination.

Meanwhile, there are still vacancies in all four U.S. attorney positions in California. The Trump administration has only nominated a candidate for the eastern district, which is based in Sacramento: McGregor Scott, who held the position during the Bush administration and has received Feinstein’s backing.

“It’s been a slow process — and nobody knows what’s going on,” said Chuck La Bella, a San Diego lawyer who served as U.S. attorney in the southern district during the Clinton administration. U.S. attorneys are typically nominated within the first year of a presidency, he said.

Judicial nominations — typically under-the-radar affairs for seats below the Supreme Court — got a jolt of attention last week when the Senate Judiciary Committee approved a 36-year-old Trump administration lawyer who had never tried a case and included his time as a “paranormal investigator” on his Senate questionnaire for a federal judgeship in Alabama. Trump has also raised eyebrows in the legal world for moving forward with judicial nominees without waiting for assessments from the American Bar Association, which typically evaluates all potential judges.

Harmeet Dhillon, a San Francisco lawyer and RNC National Committeewoman for California, insisted that Grassley’s decision on blue slips doesn’t mean he’s cutting Democrats out of the process completely.

“Sen. Feinstein and Sen. Grassley have served on that committee for decades,” she said. “I would suspect you’ll continue to see substantial courtesy given from Sen. Grassley to Sen. Feinstein.”