Mitt Romney has admitted that a failure to connect with minority voters and his underestimation of support for Barack Obama‘s healthcare reforms helped cost him the presidential election – an assessment that could have important implications for a Republican party divided over how to take back the White House.

Romney said the alienation of Latino and black voters did “real damage to my campaign”.

“We weren’t effective taking our message to primarily to minority voters, to Hispanic Americans, African Americans, other minorities.

“That was a failing. That was a real mistake,” he told Fox News Sunday in his first major interview since his defeat in November.

Romney also conceded that he underestimated support for the president’s healthcare reforms which he campaigned to repeal.

“Obamacare was very attractive, especially to those who did not have health insurance, and they came out in large numbers to vote,” he said.

The acknowledgement will be seized on by sections of the Republican party which believe it has to connect with Latino and younger voters in particular if it is to stand and not lose ground in congressional and state elections, especially in regions with a rapidly rising number of Hispanic voters.

Some Republicans, such as senator Marco Rubio, are urging the party to move away from anti-immigrant legislation and hostile rhetoric that played particularly badly with Hispanic and other minority voters.

But Romney said he would not be the man to be telling his party what to do on that or other issues.

“I lost, and so I’m not going to be telling the Republican party: come listen to me, the guy who lost,” he said.

Romney said “it kills me” to have lost the election to Obama but took personal responsibility for the defeat saying it was “because of my campaign not because of anything anyone else did”.

He conceded that he damaged his own campaign badly with the notorious comment about 47% of voters who will vote for Obama because they “believe that they are victims” who pay no income tax. He said at the time that “my job is not to worry about those people”.

On Sunday, Romney said he had not meant what he said but recognised it had hurt him.

“It is not what I meant. I did not express myself as I wished I would have,” he said. “It was very harmful. What I said is not what I believe. That hurt. There is no question that hurt and did real damage to my campaign.”

However, Romney denied what was characterised by the Obama campaign as his flip-flopping on issues in order to first woo conservative Republican primary voters and then shifting to appeal to the broader electorate in November.

“The idea that somehow the primary made me become more conservative than I was just isn’t accurate,” he said. “On the other hand, a long and blistering primary, where people are attacking one another and where the attack sometimes are not on the mark but are creating an unfavourable impression, those things are not helpful.”

Romney said he was “convinced we would win” right up until election day but knew his bid for the White House was doomed when the exit polls from Florida, which he expected to win handily, showed a tight race.

Obama took Florida with a clear majority, but by then the president had also won Ohio and Romney said he then knew he’d lost for sure.

Romney joked that at least in 2012 he was the Republican candidate after failing to win the party’s nomination four years earlier, but said he will not make a third run.

The Republican former candidate waded into the latest Washington crisis, expressing frustration at what he described as Obama’s failure of leadership over the $85bn in automatic cuts which kicked in on Friday under the sequester after Republicans and Democrats failed to agree a package of spending reductions and tax increases to tackle the US deficit.

“It kills me not to be there, not to be in the White House doing what needs to be done,” he said. “What we’ve seen is the president out campaigning to the American people doing rallies around the country, flying around the country, and berating Republicans and blaming and pointing. That causes the Republicans to retrench and then put up a wall and to fight back. It is a very natural emotion.”

Romney’s wife, Ann, appeared alongside him for the interview. She said she is still frustrated that “people didn’t really get to know Mitt for who he was”, which she blamed on the campaign and the media. She said that she was asked to appear on Dancing with the Stars after the election but turned it down because of her age.

“I’m not really as flexible as I should be,” she said.