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Senator Marco Rubio of Florida won the endorsement on Friday of The Las Vegas-Review, Nevada’s largest newspaper, an important boost in a state that could play a key role in his efforts to win the Republican presidential nomination.

But the endorsement is significant not just in what it says in glowing terms about Mr. Rubio — calling him the “best-positioned to advance from the primary season and allow the G.O.P. to win the White House” — but for what people will read into it as a potential harbinger of the preferences of the paper’s new owner, Sheldon Adelson.

Mr. Adelson is one of the most generous contributors to Republican candidates, but he has yet to publicly pick a favorite in the presidential contest, making his choice a matter of great intrigue. People close to Mr. Adelson, who owns Las Vegas properties like the Venetian, say he is fond of Mr. Rubio. The two met in Las Vegas in December.

The Review-Journal said in its editorial that the Adelson family had no input in the endorsement. “The Adelsons have detached themselves from our endorsement process, and our endorsement of Sen. Rubio does not represent the support of the family,” the paper wrote.

The Republican caucuses in Nevada are on Feb. 23, three days after the South Carolina primary. Mr. Rubio, who spent part of his childhood in Las Vegas, has built a considerable campaign operation in the state. A strong finish there, while not packing quite the punch as a first- or second-place finish in one of the other early-voting states, would reinforce the sense that Mr. Rubio’s campaign is building momentum.