The government remains "committed" to reform of the Royal Mail through the Postal Services Bill, MPs have been told.
During the Business, Innovation and Skills questions business minister Pat McFadden said: "The challenges faced are real in terms of the pension fund deficit and the need for investment and change."
McFadden explained that the government had a duty to secure "best value for money" for the taxpayer. "We remain committed to the legislation," he insisted.
But shadow business secretary Ken Clarke accused the government of delaying the legislation because of "internal political division" within the cabinet.
"This is the acid test of whether this lame-duck government is capable of delivering on difficult decisions," he said.
The Bill's second reading was expected two days ago.
Clarke also poked fun at the new department, describing it as Lord Mandelson's "amazing ever-expanding empire", and suggested the business secretary no doubt had “other territorial ambitions” in mind.
Liberal Democrat business spokesman John Thurso said the Postal Services Bill appeared to have "disappeared into the legislative ether".
He called on McFadden to bring forward the regulatory tool kit section of Bill as it had "particular importance" for the future of the service.
He noted that this particular aspect of the Bill had been agreed by all parties.
McFadden agreed that the proposal to maintain "universal service" was at the heart of the proposed system.
"I would remind the House that conclusion drawn by Richard Hooper was that if we did not change and reform the Royal Mail that service would be under threat," he said.
The government also faced questions on the appointment of Sir Alan Sugar to the post of 'business tsar'.
McFadden praised Sugar as one of Britain's "most well-known and respected entrepreneurs".
He argued that in a time of economic crisis it was important to draw on all available talent.
Shadow skills minister David Willets criticised the merging of business and education under the new department.
"We believe that our colleges and universities are not simply the instruments of a business department," he said
He also asked for assurances that young people already enrolled on apprenticeship schemes would not lose their place in light of the recession.
"At the moment the biggest single victims [of the recession] are young people," he argued.
Newly appointed minister Ian Lucas said that it was "inevitable" that there would be redundancies during an economic downturn, but said that where possible alternative apprenticeship places would be found.
MPs from all sides of the Commons pressed ministers on funding for further education colleges.
Shadow business minister David Evennett said that many colleges were having to use "substandard" teaching facilities due to the mismanagement of the capital programme.
Kevin Brennan, minister of state at the department for business, innovation and skills, argued that there had been more students in porter cabins under the previous Conservative government than there were now.
"I'm afraid that if they came back to power there would be more of the same," he added.
Shadow business minister Mark Prisk claimed that red tape was "strangling enterprise".
Prisk said that businesses wanting to install micro-generation had to comply with five separate regulators.
"Is this burden of regulation intentional or the result of incompetence," he asked.
Lucas said it was "never the intention" of government to create difficulties.
The minister also sought to assure MPs that the new department remained committed to regulatory reform, despite the dropping of the phrase from the name of the department.
"I will be doing all I can to remove unnecessary regulation from small business," he said.
