Gordon Brown and his wife Sarah are met by cheering party supporters
Labour must expose the Tories, Welsh Secretary Peter Hain said on the eve of the party's last major conference before the general election.
The Tories had been "given an easy ride by everybody," he said.
Meanwhile, Gordon Brown was greeted by cheering Labour activists as he arrived in Brighton for the conference.
BBC political correspondent Iain Watson said the prime minister still had to convince some delegates that he was the right man to lead Labour into the poll.
Mr Hain said: "We need to get off the back foot, we've been there for too long, and get on the front foot and start putting our policies forward and also start exposing the Tories.
"They've had such an easy ride from everybody, yet their policies would wreck the recovery that is now in sight because they would mount massive, swingeing, savage - in their words - public spending cuts."
Schools Secretary Ed Balls insisted the prime minister's "authentic" approach would find favour with voters.
But ex-deputy PM John Prescott has accused Labour MPs of defeatism.
Accompanied by wife Sarah, a beaming Mr Brown shook hands with his deputy, Harriet Harman, and Labour General Secretary Ray Collins as he arrived at his hotel in Brighton.
The prime minister said nothing to reporters waiting in the warm September sunshine.
Senior Labour figures have also indicated that the prime minister may hold a television debate with opposition leaders during the general election campaign - a move which Conservative leader David Cameron said he would welcome.
Mr Brown is expected to unveil in his speech on Tuesday a promise that patients in England will get key cancer tests within two weeks of seeing their GP.
His aides say he will pledge that GPs in England will get speedier access to diagnostic tests to help spot less clear-cut cancer cases.
The policy will be funded from savings worth £1bn from the NHS's capital budget over five years.
We've got a whole bank of MPs, but everybody seems despondent
Our correspondent added that the prime minister is also expected to claim credit for economic recovery during his address to delegates.
The conference follows a summer in which Mr Brown has faced criticism for writing a letter of congratulations to England's victorious Ashes cricket team while keeping silent on the release of the Lockerbie bomber Abdelbaset Ali Mohmed al Megrahi.
And as delegates gathered for the conference, which begins on Monday, Mr Prescott suggested in his interview there was a lack of talent and experience among the party's team of advisers.
Mr Prescott told the Independent there was "something lacking" at the top of the party.
He said: "Those who have responsibility for campaigning - it is not reaching out to the depths of the party.
"We've got a whole bank of MPs, but everybody seems despondent. There's too much defeatist thinking. There's no central direction to campaigning."
"There's got to be leadership and there's got to be a message."
'Fighters, not quitters'
But in interviews for Saturday's morning newspapers, cabinet ministers fell behind the prime minister and talked up the party's chances at the general election.
Energy Secretary Ed Miliband told the Daily Telegraph that Mr Brown was "the right leader" and said the prime minister had "bags" of resilience to take into the next election.
Mr Balls - regarded by many as the prime minister's closest ally - insisted there was "all to play for" at the polls.
He told the Guardian the prime minister should not worry about lacking "razzmatazz" and said the party needed "more fighters, not quitters".
Question Time in the House of Commons is no substitute for a proper television debate
David Cameron Conservative leader
Mr Balls added: "Gordon is who he is. Gordon is at his strongest when he is being authentic."
The schools secretary also said he believed Labour could benefit from a proposed direct debate with Tory leader David Cameron.
"The more debates the better," Mr Balls said.
"David Cameron is better at reading out a script than discussing the detail of policy."
International Development Secretary Douglas Alexander said Mr Brown had "nothing to fear" from a TV debate between the party leaders.
Mr Alexander, who is also Labour's election co-ordinator, suggested to the Daily Mirror that any televised debate could be part of a series between Labour heavyweights and their opposite numbers ahead of the next general election.
Mr Cameron said he was keen for the encounter, arguing it would engage the public.
He added: "Question Time in the House of Commons is no substitute for a proper television debate.
"Gordon Brown should make a decision about this. There's either a 'yes' or a 'no'. My answer's 'yes' - what's his answer?"
This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.