The presidential campaign of Texas Rep. Ron Paul is calling it “underhanded” and “completely unacceptable” that the Nevada GOP has scheduled a special evening caucus in Las Vegas on Feb. 4 to accommodate billionaire casino magnate Sheldon Adelson.

Carl Bunce, Nevada campaign chair to the Paul campaign, reacted forcefully to a Chronicle report that the state GOP Thursday confirmed the decision to go ahead with the special caucus beginning at 6 p.m. A party official told the Chronicle the special caucus would “accommodate those with religious restrictions.”

But the Nevada GOP has raised eyebrows with its move to provide a special evening caucus session at the Adelson Educational Campus, a private school in Las Vegas founded by Adelson. State Republicans told the Chronicle the decision came after pressure from the billionaire who donated $5 million to a special PAC in support of GOP presidential candidate Newt Gingrich — a donation that was matched by his wife, Miriam.

Adelson, one of the world’s richest men, is an Orthodox Jew and observes the Sabbath from sundown on Friday until sundown on Saturday. The special Adelson caucus would reportedly accommodate some 500 conservative observant Jewish voters who presumably also would be observing religious traditions on Saturday morning.

Bunce said in an email to the Chronicle that it appears Gingrich, lacking organization and campaign efforts in the Silver State, is “going to have his billionaire buddy try and buy an election for him.”

State GOPers say many as 50,000 Nevada GOP voters are also expected to participate in the Feb. 4 caucuses. The general population is instructed to take part in caucuses Saturday morning starting in various locations from 9 a.m. to noon.

Under Nevada caucus rules, there’s no absentee voting allowed; if voters are working or unable to attend because of business or personal issues, they can’t participate.

Given the tight squeaker of a finish at the Iowa caucuses, where former Pennsylvania Sen. Rick Santorum only barely edged out a win over former Massachusetts Gov. Mitt Romney, insiders say — while it’s unlikely — such a change to accommodate a specific group of voters could potentially change the outcome.

An official with the state Romney campaign said Thursday that there’s concern that the evening caucus would delay results, and that residents in other counties may have reason to challenge preferential treatment. Clark County, home to Las Vegas, is the state’s most populous region with 70 percent of the state’s residents.

Bunce, in his email to the Chronicle Thursday, that the Paul campaign — which has an aggressive turnout effort in the state — is challenging the decision.

He said the campaign is “working with the Nevada State Republican Party to fix the situation, to either stop it completely or move the location to someplace other than Mr. Adelson’s private school, where he is able to do whatever he wants to promote a get out the vote event for the candidate of his choice.”

Bunce said he has heard from many state Republicans who believe the decision is unfair to thousands of other Nevadans who may be “unable to get off work to particpate in the moring caucuses, but are also unable to participate in this evening event because of the religious test that is required to allow people to vote.”

A state party official told the Chronicle Thursday that said no other caucuses are planned in Nevada to accommodate religious voters. He deferred any other questions to a press call planned for Friday in which he said state party officials would outline the caucus process and scheduling.