If Senate confirmation of Supreme Court nominee Brett M. Kavanaugh comes down to a single vote, Sen. Steve Daines of Montana could keep the world waiting for hours on Saturday.

There is no doubt that Daines, a Republican, will vote to confirm Kavanaugh when the final vote is called, but his personal calendar is a complication: His elder daughter, Annie, is getting married Saturday in Montana.

“At the end of this weekend, I will have walked my daughter down the aisle at her wedding and there will be a new Supreme Court justice,” Daines told reporters Friday. “We’ll wait and see how this all unfolds here.”

The most likely outcome, according to a senior GOP aide familiar with the discussions, is that the vote will be held open — potentially for hours — while Daines flies back east.

The spectacle of Republicans holding open a politically charged vote for a decisive absentee to return to Washington is likely to feed the anger of Kavanaugh’s critics, many of whom have been protesting on Capitol Hill for days.

Such a step has Senate precedent. In 2009, a key vote on President Barack Obama’s fiscal stimulus package was held open for hours to allow Sen. Sherrod Brown (D-Ohio) to return on a military jet from a visitation for his recently deceased mother.

But, given the controversy the nomination has unleashed, a delay into the wee hours Saturday night or Sunday morning could produce further protests and possible disruptions in the Senate chamber.

Under Senate rules, the final confirmation vote is set to be called 30 hours after the Senate votes to cut off debate — setting up a vote shortly after 5 p.m. Saturday on Kavanaugh’s confirmation. Pushing back the start of the vote would require agreement of all 100 senators, an unlikely prospect considering the rancor in the Senate.

If the vote tally from Friday’s procedural vote holds Saturday, Daines’s vote would not be needed. Kavanaugh could be confirmed 50 to 49.

But if any senator changes his or her vote — say Sen. Susan Collins (R-Maine) or Sen. Joe Manchin III (D-W.Va.) — Daines’s vote would be the 50th, setting up a tiebreaking vote by Vice President Pence.

Sen. John Thune (R-S.D.), the No. 3 Republican leader, said he was not certain how things would play out.

“That’s something that at this point is a little bit of an unknown in terms of, if the vote does come off at 5 or 5:30, how much time does it take to get him back from Montana?” he said. “Can the vote be pushed? Can it be kept open? Those are all things we’ll have to sort out over the next 24 hours.”

Daines said Friday that he has made travel arrangements to get back to Washington after the wedding but did not detail what they were or how long his trip might take.

“We have transportation ready,” he said, declining further comment. In a tweet, he said that Rep. Greg Gianforte (R-Mont.) has offered the use of his plane.