Gordon Brown should not have taken The Sun's switch of support from Labour to the Conservatives "so personally", Lord Mandelson has said.
Giving evidence to the Leveson inquiry on Monday, the former Labour business secretary said News International simply saw "greater commercial interest" in the election of a Conservative government than a Labour one.
"I'm afraid a Labour government coming to the end of 12 or 13 years of office had been buffeted by events and by changing electoral attitudes," he said.
Lord Mandelson added: "He [Brown] shouldn't have taken it so personally, this is politics.
"My view was shrug it off, don't dignify them with tears, crocodile or otherwise."
Lord Mandelson said he thought Labour should ignore The Sun and "get on with life" and fight the general election.
After supporting Labour since 1997, The Sun decided to switch its support to David Cameron and the Tories in the run-up to the 2010 election.
The paper made the announcement during the Labour Party's last conference before voters went to the ballot box.
Rebekah Brooks told Leveson earlier this month that the paper decided in part to switch it support after Brown failed to devote enough time to the war in Afghanistan in his conference speech.
"We felt that was the right timing in order to distance ourselves," she said.