Deputy Prime Minister Barnaby Joyce was forced to turn his attention from one political fight to another for a moment this week.

Mr Joyce, who's facing a stern contest with former independent MP Tony Windsor in his northern NSW electorate, had to bat away renewed calls to halt live cattle exports.

Fresh footage of cattle being bludgeoned to death in Vietnam sparked public anger over Australia's export program and the government's perceived lack of action on curbing abuse.

The minister stood firm against suspending trade, insisting he'd instead put negligent exporters on notice.

"We are not going to ban live cattle sales to Vietnam - they are a major market for us."

Live exports are a touchy issue for locals in his tightly contested New England electorate.

Some of them have already started casting their vote as pre-polling began this week.

Mr Joyce is relying on a strong primary vote but preference flows could hand Mr Windsor back his old job.

Another key independent candidate isn't taking sides.

Rob Taber, who was Mr Joyce's main opponent in 2013, says he was told twice by Mr Windsor he wouldn't run in this election.

But that won't sway him either way.

"A true independent would never allocate preferences," Mr Taber told AAP.

That would only indicate candidates were not there for the right reasons.

"I get accused of swinging the vote but I say they're swinging the vote. It's really not me."

Mr Joyce has maintained his confidence in retaining the seat throughout the campaign.

But even some within his party aren't so sure.

In a forthcoming episode of Four Corners, former Nationals leader John Anderson is asked whether Mr Joyce could lose.

"Yes," he replies.

However, Mr Joyce will hope to have some political ammunition with speculation that former prime minister John Howard will hit the hustings with him next week.