A looming showdown over a Senate tradition could strip senators of a de facto veto power over nominees to federal appeals courts — and give President Donald Trump less reason to consult with senators about which judges should be appointed.

The Judiciary Committee’s “blue slip” process has required senators to return a blue slip of paper before the committee schedules hearings and markups of nominees for federal judgeships from their home states. No slip, no hearing. That has made it essential for the White House to get a senator’s buy-in on a nomination.

But as Democrats oppose many of Trump’s picks for the bench, Judiciary Chairman Charles E. Grassley has signaled he might end that tradition for federal appeals court choices if Democrats stand in the way.

The Iowa Republican has said the practice is not a hard-and-fast rule, and he will soon face a decision on whether the committee will move forward on two different appeals court picks without blue slips.

Democrat Al Franken announced Tuesday he would not return a blue slip for Minnesota Supreme Court Justice David Stras for a spot on the U.S. Court of Appeals for the 8th Circuit based in St. Louis.

Franken said in a written statement that Stras would be a “deeply conservative jurist” on an already conservative appeals court that covers Minnesota, Iowa, Missouri, Arkansas, North Dakota, South Dakota and Nebraska.

“But rather than work together to select a nominee who is a judicial moderate, the White House had already settled on Justice Stras before first approaching me, and the president nominated him despite the concerns that I expressed,” Franken said.

And on Thursday, Oregon’s two Democratic senators took only a few hours after the White House nominated Assistant U.S. Attorney Ryan Bounds to be a judge on the U.S. Court of Appeals for the 9th Circuit to announce they would not return blue slips.

Sens. Ron Wyden and Jeff Merkley wrote in a letter to the White House that they can’t return a blue slip for any nominee who hasn’t been approved by the state’s bipartisan judicial selection committee. They criticized the White House for demonstrating “that you were only interested in our input if we were willing to preapprove your preferred nominee.”

“Disregarding this Oregon tradition returns us to the days of nepotism and patronage that harmed our courts and placed unfit judges on the bench,” Wyden and Merkley state in their letter. “The judicial selection process is not a rubber stamp, and the insinuation that our offices were purposefully delaying the process is an indication of the partisanship with which you are pursuing this nomination.”

The 9th Circuit includes Oregon, Washington, Idaho, Montana, Nevada, California, Arizona, Alaska and Hawaii.

Chairman’s call

For now, Grassley has other nominees to send through the confirmation process before he has to make the call on whether to side with his Democratic colleagues and not move the nominees, or side with the White House and proceed with Stras and Bounds.

In May, Grassley said the blue slip process is historically more respected for district court judges — which cover districts that stay within state borders — than the circuit judges that cover multiple states.

“It’s much more a White House decision on circuit judges than the district court judges,” Grassley said during an interview on C-SPAN’s “Newsmakers” program. “I mean this is going to be an individual case-by-case decision, but it leads me to say that there’s going to have to be a less strict use or obligation to the blue slip policy for circuit, because that’s the way it’s been.”

Still, certain seats on appeals courts have by tradition been from certain states. Sen. Dianne Feinstein of California, the top Democrat on Judiciary, said the blue slips were honored when Republican senators didn’t return them on President Barack Obama’s nominees.

“In 2016 alone, President Obama’s nominations of Abdul Kallon for the Eleventh Circuit, Justice Myra Selby for the Seventh Circuit, Rebecca Haywood for the Third Circuit and Justice Lisabeth Tabor Hughes for the Sixth Circuit didn’t move forward because they didn’t receive two blue slips,” Feinstein said in a written statement.

“It’s the prerogative of home-state senators to evaluate potential federal judicial nominees and determine whether or not they are mainstream and well-suited to hold these important positions of public trust, which have real-world consequences for their constituents,” Feinstein said. “The purpose of the blue slip is to ensure consultation between the White House and home-state senators on judicial nominees from their states.”