Ms Harman's speech and David Cameron's response: from BBC Democracy Live
Acting Labour leader Harriet Harman has attacked the new coalition government as being a "loveless embrace" in her response to its first Queen's Speech.
Ms Harman said the government had "no mandate" for their plan to make sure parliament could only be dissolved if 55% of MPs backed the move.
She also said government plans for £6bn in cuts would "blight the prospects" of young people and threaten jobs.
The government's plans contain reforms to schools, welfare and Parliament.
Prime Minister David Cameron said the legislative programme was a "radical" plan to give more power to families and communities and, in contrast, Labour remained out of the touch with the public.
In her first parliamentary speech as acting Labour leader, Ms Harman said Labour would not oppose policies for "opposition's sake" but would not "pull our punches" when it disagreed with the government.
She sought to portray the new coalition government as a marriage of convenience, suggesting that Prime Minister David Cameron and his Lib Dem deputy Nick Clegg were "just not right for each other".
The Tories and the Lib Dems were "already preparing for the day when they shrink back from their loveless embrace", she told MPs.
The country will want to see that it is not they who are left bearing the cost of holding the coalition together
She attacked aspects of the government's proposed bill to reform the political system, saying fixed-term parliaments should be four not five years and said plans to make all constituencies the same size and reduce the number of MPs were designed to "rig the Commons" in favour of the Conservatives.
She also said Labour would oppose a plan to require 55% of MPs to trigger a dissolution of Parliament, which would allow a weak government to "cling onto office": "They have no mandate for that change."
Labour would be "vigilant" in its support for public services at a time of anticipated budget cuts and defend its legacy on the minimum wage, Sure Start centres and hospital waiting times.
While acknowledging reducing the deficit must be a priority for the government, she said this must be done "fairly and transparently" and criticised plans to cut university places and axe the Future Jobs Fund, part of Labour's guarantee of work or training for all 18-24 year olds out of work for six months.
'Sink or swim'
The government's tax and spending plans implied they would have to cut frontline services and raise VAT, she said - describing this as a "worrying combination".
"The challenge now for the government is to embed and secure the recovery... Where the government takes steps to do that, we will back them. But taking support away from businesses risks slower growth for the future.
"Now is not the time to leave firms to sink or swim."
She added: "The country will want to see that it is not they who are left bearing the cost of holding the coalition together."
On other proposed measures, she said Labour would resist attempts to "politicise" the police and a guarantee of a future EU referendum hid the fact the Tories and Lib Dems had irreconcilable differences over Europe.
But paying tribute to British service personnel who have died in Afghanistan since Parliament last sat, she said the opposition would "work together" with the government to support the armed forces.
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