Sir Keir Starmer has accused Reform UK of feeding off the "politics of grievance" as he held his first Cabinet meeting since last Friday's reshuffle.
The Prime Minister, who is said to have conducted a No10 reset by chopping and changing his top team, told ministers that they were the right options for the "next stage of our journey".
In a swipe at Nigel Farage's party, Sir Keir said: "It is important that we are very clear about what we’re up against.
“We’re up against those that feed off the politics of grievance, those that do not want problems to be fixed, because if the problems are fixed, their reason to exist, their politics, ceases to have any role in our society.”
The Prime Minister also encouraged his Cabinet colleagues to drive for "national renewal" across Whitehall.
He added: “And it’s them that we have in our mind’s eye as we go forward and our mission is the triumph of national renewal over divide and division and decline.
“That is our patriotic responsibility and our patriotic duty.
"And I look forward to working with all of you as we go on to this next phase of government."
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Sir Keir Starmer held his first Cabinet meeting since a reshuffle last week prompted by Angela Rayner's resignation
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Ministers around the Cabinet table included Education Secretary Bridget Phillipson, who has launched her bid to replace Angela Rayner as Labour's deputy leader.
Ms Phillipson is so far the early frontrunner in the leadership race, beating five other candidates to secure the most nominations from MPs so far.
The Education Secretary had the backing of 44 colleagues as of 6pm on Tuesday, the first official tally after nominations opened shows.
Former Commons leader Lucy Powell, who was sacked by Sir Keir Starmer in his reshuffle, is close behind with 35 of the 99 overall nominations.
Bridget Phillipson is currently leading the race for Labour's new deputy leader
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Backbencher Bell Ribeiro-Addy has eight, Commons Foreign Affairs Committee chairwoman Dame Emily Thornberry seven, Paula Barker three, and housing minister Alison McGovern comes last with two nominations.
The candidates have until 5pm on Thursday to secure the support of 80 MPs in order to reach the next round of the contest.
The deputy leadership contest could trigger a round of infighting within Labour as the party tries to find a way to reverse plummeting opinion poll ratings.
Divisions within Cabinet could also become clear as Chancellor Rachel Reeves works on a Budget which could involve tough choices as she tries to cut costs or raise taxes to fill a black hole in the public finances.
But Sir Keir stressed that everyone around the Cabinet table has to be part of a “team effort”.
He told the Cabinet meeting: “We are obviously representing different departments around the table, as you must and you will, but you’re not just representing one department. You are representing the Government.”
Aside from Sir Keir’s opening remarks, the Cabinet meeting took place behind closed doors as normal.
The Prime Minister stressed everyone around the Cabinet table has to be part of a 'team effort'
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The Prime Minister said the Government had to demonstrate to people it was “driving down costs and spending their taxes well”, according to Downing Street’s account of the meeting.
That included measures to go “further and faster in reducing the size of the civil service” and “reducing the number of regulators”.