Bill Shorten has acknowledged the minerals resource rent tax had damaged his party's relationship with the resources sector, and has refused to express confidence in the underperforming law.
He said Labor would go about rebuilding links with the industry before the next election.
The concession reflects an acceptance that the new Senate, to sit from July, will repeal the tax, which raised just $232 million last financial year despite being tied to $12.6 billion in new expenditure through benefits such as the schoolkids bonus.
The Labor shift fuelled hopes in the government of a repeal before July but Mr Shorten's office dashed those, declaring Labor would continue to block a repeal in the Senate.
However, the Shorten shift has increased the likelihood that Labor will abandon any proposal to re-introduce a resources rent tax or for that matter a carbon tax, at the next election.
Labor recently broke ranks with the Greens, deciding not to support a disallowance motion against cancelling carbon credit auctions - a key part of the carbon price framework.
The government characterised that as the key moment when Labor's resistance to the new political reality crumbled.
Campaigning in Perth for the coming state-wide byelection on April 5, Mr Shorten said only that the ''principle'' of a profits based resources tax was sound, but its introduction had been destructive.
''Labor will over time have to reach out to the resources sector. We're looking forward to doing that over the next two years,'' he said.
But asked repeatedly if the MRRT was still backed by Labor, Mr Shorten opted to deflect.
Mr Shorten also appeared to change tack on border protection, dropping Labor's previously clear condemnation of the Abbott government's boat turn-around policy after more than 80 days of zero boat arrivals in Australia.
Asked during the interview on Sky News if Labor remained absolutely opposed to the turn-arounds, Mr Shorten said it was the lack of transparency that the opposition objected to.