Sen. John Barrasso of Wyoming is seeking another term as the Senate’s No. 2 Republican leader, urging colleagues to unite around a clear alternative to Democrats after the party lost control of the chamber in last week’s elections.

In a letter to Republican senators on Monday, Barrasso acknowledged that the party had endured a “difficult night” on Election Day. He said Republicans have “both an obligation and an opportunity to demonstrate that we heard the unmistakable message voters sent.”

Barrasso, the current Senate GOP whip, is expected to run unopposed in Tuesday’s leadership election. His bid comes as Republicans debate their path forward following sweeping losses and prepare to serve as the Senate’s opposition party.

“As the opposition party in the Senate, we must be equally clear about what we stand for and what we will fight against,” Barrasso wrote in the letter, a copy of which was obtained by POLITICO. “We need to draw sharp, principled contrast with the left-wing Majority.”

The Wyoming senator also addressed the balance between working across party lines and maintaining Republican priorities. While “bipartisan accomplishments matter,” he wrote, “bipartisanship cannot come at the expense of our principles.”

His appeal comes amid an effort by a group of conservative senators, led by Wisconsin Sen. Ron Johnson, to postpone the leadership elections. The group has requested a conference meeting Tuesday morning to discuss a delay.

Barring a broader revolt that few Republicans expect, South Dakota Sen. John Thune is expected to be reelected as the party’s top Senate leader later Tuesday.

Barrasso did not address the calls for a postponement in his letter. Instead, he emphasized the importance of cooperation within the Republican conference over the next two years, saying its effectiveness would depend on senators’ ability to work together, make difficult decisions and communicate openly.

“Every Senator deserves to be heard. Every concern deserves consideration,” Barrasso wrote. “We will not agree on everything, but we remain united in our purpose.”