The Times of London reported. Miliband on Thursday backed Brown, saying, "We are all determined to win the election under Gordon's leadership."
On Wednesday, however, Miliband seemingly offered a less-than-enthusiastic backing for Brown after another attempt at the prime minister's ouster.
"I am working closely with the prime minister on foreign policy issues and support the re-election campaign for a Labor government that he is leading," Miliband said.
Former ministers Geoff Hoon and Patricia Hewitt on Wednesday called for a secret ballot on Brown's leadership, an effort dismissed by Northern Ireland Secretary Shaun Woodward as a temporary distraction.
"What happened yesterday was without question unfortunate; it was a distraction," Woodward told the BBC. "But what we know this morning, 24 hours later, is that this is a party that wants Gordon Brown as leader."
Tory leader David Cameron seized on the apparent divisions within the Labor Party, saying Brown was in "deep trouble" while renewing calls for an immediate general election.
"You just have to ask yourself, 'How much time do you think senior ministers spent yesterday thinking about the budget deficit, about the education of our children, about the war in Afghanistan, and how much were they thinking about their own careers' for you to realize that ... we cannot go on like this," Cameron said. "We've got to have an election and a change of government."