Tony Windsor's wife "deeply upset" over political ad implying he cheated on her.

The fight for the NSW seat of New England has reached new heights after Tony Windsor accused Barnaby Joyce’s camp of suggesting he had cheated on his wife in the latest Nationals campaign ad.

Independent candidate Windsor has called for an apology from the Nationals leader and demanded the withdrawal of the “offensive gutter ad” which he says has “deeply upset” his wife.

The ad depicts two women chatting over coffee when one receives a text message from Windsor that reads: “Hey New England, how about another chance?”

“He wants me to take him back,” the woman tells her unimpressed friend. “It was okay for a time, I guess. ”

Her friend then reminds her: "Yeah, but then he ran off with Julia," referring to Windsor's key support of the former minority government headed by Julia Gillard.

The woman then says while she "sometimes" misses him, "things have changed and I've moved on."

"And you're doing so well without him," the friend says.

The woman recalls it ended "badly" last time, says she doesn't know "how serious he is" and agrees she can do better.

The ad ends with her replying via text message: "Not this time, Tony."

In a statement, Windsor said: "They can throw whatever criticism at me but when it involves and upsets my family that's another matter."

In a tweet, Windsor also appeared to imply both Joyce and his campaign chairman James Treloar were up to their own philandering. It is understood he later revoked the claim.

Joyce & Treloar shd withdraw offensive gutter ad inferring philandering with women. These two should be the last to raise this issue #auspol

— Tony Windsor (@TonyHWindsor) June 26, 2016

The Nationals have rejected Windsor's interpretation as "faux outrage" and have refused to remove the ad which they say only suggests Windsor has been unfaithful to the New England electorate - not his wife.

"(The) ad is clearly tongue-in-cheek and in no way does it seriously suggest that Tony Windsor is or has ever been in a romantic relationship with the character in the commercial. Any reasonable person can see that immediately," Nathan Quigley, the state director of Nationals NSW, said in a statement.

As the battle to win over voters in the seat of New England heats up, both sides have been busy smearing each other.

The Nationals claim Windsor has five attack ads in New England versus their one, and say Windsor declined an offer "for both sides to withdraw all negative material", ABC reports.

The latest Newspoll shows Joyce leading Windsor 51 per cent to 49 per cent.

Yesterday, deputy PM Joyce posted a video on Facebook showing two farmers who worked in "snow and sleet" to remove stickers that read "Member for Rhineheart" on his billboards.

Today, Windsor said he had called in his lawyers over an article on the front page of The Australian alleging he was a schoolyard bully in his childhood.