"Change is coming," Sir Keir Starmer has told Labour activists on the eve of the party's conference in Liverpool.
The gathering follows a gloomy few weeks for the government after questions over donations over clothing and gifts, and damaging briefings over the operation in No 10.
Starmer, deputy PM Angela Rayner, and Chancellor Rachel Reeves have been criticised for accepting donations of thousands of pounds worth of clothing from donors including Labour peer Waheed Alli - a practice they have now said will stop.
On Saturday, Cabinet Minister Lucy Powell told the BBC Labour was "not in hoc" to vested interests "at all", and had declared donations correctly.
She said Labour was "taking on" water companies, rail companies and the football clubs, adding "we're on the side of fans, we're on the side of consumers, we're on the side of ordinary people".
Labour supporters are gathering ahead of the first conference the party has held as the party of government for 15 years.
Starmer and Rayner have had meetings with unions who contribute to the party coffers, amidst doubts some have about the green agenda and how policies can fit with the future of traditional industries.
Gary Smith, the general secretary of the GMB, warned the party leadership it must listen to union voices.
"Labour now in government haven’t faced the harsh realities," he said.
"If Labour fails to listen to us on the issues about real jobs in places like oil and gas, and steel, and manufacturing and industry, the difficulty they will have is communities will get hollowed out, people will lose their jobs and the only winners will be the far right in this country."
Some unions are also known to have concerns about legislation to toughen up workers' rights, particularly calls for workers' rights "from day one".
Powell confirmed Labour's manifesto pledge to introduce workers' rights legislation in the first 100 days of the government would go ahead.
Describing the legislation as "a big package" that would be "the first step towards rebalancing our economy", she added it would be “big and bold and transformatory”.
The union Unite is also seeking to pile pressure on Reeves' unpopular decision to cut winter fuel payments to 10 million pensioners this season, with a potential vote on the issue on the conference floor on Monday.