Andrew Sidamon-Eristoff

Then-New Jersey Treasurer Andrew Sidamon-Eristoff is shown in a file photo.

(Aristide Economopoulos | NJ Advance Media For NJ.com)

TRENTON -- A former state treasurer under Gov. Chris Christie, a top adviser to Republican presidential nominee Donald Trump, will run the New Jersey campaign for Gary Johnson, one of the third-party candidates challenging Trump for the White House.

Andrew Sidamon-Eristoff will serve as the Garden State chairman for Johnson, the Libertarian Party's nominee, the party announced Friday.

The news comes about a month after Sidamon-Eristoff, a longtime Republican, announced he was breaking from the party to back Johnson over Trump. He reaffirmed that stance in a statement Friday.

"To be clear: I have always been and remain a loyal Republican," Sidamon-Eristoff said. "But partisan loyalty should not be blind or unconditional."

"As an American who believes strongly in maintaining the integrity of, and confidence in, our political processes and public institutions, I cannot in good conscience support my party's nominee for President, he added. "Nor can I support a Democratic Party nominee who does not share my Republican values or priorities."

Sidamon-Eristoff, a Princeton resident, was the top state treasury official from 2010 to 2015 under Christie, who runs Trump's transition team.

He also worked under former New York City Mayor Rudy Giuliani, another top Trump adviser. Sidamon-Eristoff served on the New York City council from 1993 to 1999 and then worked in Giuliani's cabinet as the city's commissioner of finance from 1999 to 2002.

Polls show Johnson, the former New Mexico governor, is running a distant third to Trump and Hillary Clinton, the Democratic nominee.

A recent CNN/ORC International poll showed Trump drawing 45 percent of registered voters, Clinton drawing 43, and Johnson drawing 7.

Brent Johnson may be reached at bjohnson@njadvancemedia.com. Follow him on Twitter @johnsb01. Find NJ.com Politics on Facebook.