(CNN) - Just two days before the Nevada caucuses Donald Trump announced his presidential endorsement for Mitt Romney. But will the real estate mogul's stamp of approval mean anything to Republicans?
According to a survey conducted January 5-8 among 1,000 adults, by the Pew Research Center for the People & the Press and The Washington Post, most Republican and Republican-leaning voters say a political endorsement by Trump doesn't make any difference to them.
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The survey found that 64% said Trump's endorsement would not affect their vote, while the rest of those polled had mixed reactions: 20% said they would be less likely to support a candidate that Trump backed and 13% more likely.
"Endorsements rarely sway voters when the candidates are already well known and defined," said CNN contributor and Republican strategist Alex Castellanos.
"In today's world of 19 debates, thousands of TV ads and endless cable coverage and internet commentary, voters feel they have more than enough information to make up their own minds."
Regardless of Trump's endorsement, Romney holds a huge lead in Nevada. The Las Vegas Review-Journal and 8NewsNow poll released Thursday showed Romney with 45% support followed by Gingrich with 25%, Rick Santorum with 11% and Ron Paul with 9%.
And if Nevada is anything like Florida, a last-minute endorsement won't sway many voters from their decisions.
Former GOP candidate Herman Cain announced his endorsement for Newt Gingrich just three days before Tuesday's Florida primary which Romney won easily.
The survey found that the impact of Cain's endorsement also generated a mixed reaction among Republicans - 17% said they would be more likely to vote for a Cain-backed candidate and 15% less likely.
But Trump's endorsement does differ from Cain's.
First, Trump is a reality TV star with nearly 1 million Twitter followers. Secondly, Republican candidates have courted Trump for his endorsement since 2011 when several of the candidates made individual rendezvous with The Donald at Trump Tower in New York to - as then-candidate Jon Huntsman put it - "kiss his ring."
Trump wrote in his book "Time to Get Tough; Making American No. 1 Again" that it wouldn't surprise him if he's the "single most important endorsement a presidential candidate" can get.
The Pew survey disagrees.
The two big endorsements that could influence voters would come from former President George W. Bush and 2008 GOP vice presidential candidate Sarah Palin. Nearly three-in-10 (28%) surveyed by Pew said they would be more likely to vote for a candidate that Bush supported, and 11% would be less likely. Palin's endorsement would also have a positive impact on Republican voters with 23% saying they would support a candidate who Palin backed and 15% less likely.
But even endorsements from Bush and Palin wouldn't make a difference to most Republican voters, according to the survey. Neither would endorsements by the governor of their state, their local newspaper, or their minister, priest or rabbi.
While Trump's endorsement might influence the GOP race, it will raise awareness of him three weeks before the season premiere of his NBC show "The Celebrity Apprentice."