Crumbling relationships and differences on climate policy have prompted Nationals stalwart Barnaby Joyce to call time on his New England seat.

Amid speculation of a move to One Nation, the former leader of the Nationals said it had become untenable for him to remain in the party room and that relationships with leaders had deteriorated beyond repair.

"My relationship with the leadership of the Nationals in Canberra has unfortunately, like a sadness in some marriages, irreparably broken down," the former deputy prime minister wrote in a letter to branch members.

Mr Joyce was relegated from the party's frontbench by current leader David Littleproud earlier this year.

The statement confirmed the veteran MP will see out the rest of the parliamentary term but not stand for his New England s

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