President-elect Donald Trump is demanding a new form of presidential power to expedite the appointment of his Cabinet, which is also now potentially defining this week’s battle to lead the Senate GOP.

In a social media post on Sunday, Trump – who had said little about the race for Senate majority leader – said any Republican senator vying to be leader “must agree to Recess Appointments” to get his nominees “confirmed in a timely manner.”

“Any Republican Senator seeking the coveted LEADERSHIP position in the United States Senate must agree to Recess Appointments (in the Senate!), without which we will not be able to get people confirmed in a timely manner. Sometimes the votes can take two years, or more. This is what they did four years ago, and we cannot let it happen again. We need positions filled IMMEDIATELY!” Trump posted on X.

Trump’s demand for recess appointments, which would allow his nominees to essentially bypass Congress, resurfaces a decades-old clash between presidents and Capitol Hill leaders — one in which the Supreme Court has previously weighed in favor of the Senate’s powers.

One obstacle to Trump’s wishes is that both chambers have to pass a resolution to go into recess, which would give Senate Democrats an opportunity to filibuster the resolution and essentially block its passage. During Trump’s first term, for example, he was blocked by the Senate from using recess appointments to replace then-Attorney General Jeff Sessions.

But if the incoming Senate GOP leader did back the idea, it would be notable support for expansion of presidential power, even for a leader in the same party as the president-elect. In past decades, senators of both parties have been skeptical of the practice.

So far, at least one Republican seeking to lead the Senate GOP conference has firmly backed the idea. Florida Sen. Rick Scott on Sunday quickly posted on X endorsing Trump’s post : “100% agree. I will do whatever it takes to get your nominations through as quickly as possible.” Trump ally Elon Musk then praised the Florida Republican, writing on X: “Rick Scott for Senate Majority Leader!”

South Dakota Sen. John Thune, who’s also running in Wednesday’s secret-ballot election to be leader, posted on X later Sunday that “all options are on the table” to quickly confirm Trump’s nominees.

“We must act quickly and decisively to get the president’s nominees in place as soon as possible, & all options are on the table to make that happen, including recess appointments. We cannot let Schumer and Senate Dems block the will of the American people,” Thune wrote.

CNN has reached out to Thune and Sen. John Cornyn of Texas, another members of leadership who is running for leader.

Also on Sunday, Trump called on Senate Republicans to block any attempt by the current Democratic-controlled Senate to push through more judges before the balance of balance changes.

Trump posted: “Additionally, no Judges should be approved during this period of time because the Democrats are looking to ram through their Judges as the Republicans fight over Leadership. THIS IS NOT ACCEPTABLE. THANK YOU!”

But Democrats will control the chamber for the rest of Biden’s presidency and do not need GOP votes to approve judges.

The question of recess appointments will now throw a major wrench in the Senate GOP’s leadership election when senators return to Washington this week.

Recess appointments were once controversial, last-ditch efforts for presidents to install their nominees after facing long confirmation odds in the Senate. President George W. Bush appointed John Bolton as US ambassador to the United Nations via a recess appointment, for example, as it was unlikely he would have made it through the Senate.

Senate Majority Leader Harry Reid, the Democrat leading the Senate under Bush, then decided to make it so that the chamber simply never recessed long enough for such an appointment to be made. When senators left town, the Senate held a “pro forma” session to prevent any recess appointments.

This was continued under then-Senate Majority Leader Mitch McConnell and then-President Barack Obama — a clash that made it to the Supreme Court. And after the court ruled in favor of the Senate’s powers, the pro forma sessions continue today.

CNN’s Ted Barrett and Sarah Ferris contributed to this report.