David Axelrod, the political strategist who helped Barack Obama secure two terms in the White House, has warned that racial “fear” and hostility toward the first black US president has infected American politics and is partly to blame for Republican intransigence in confronting the president’s agenda.

In an interview with the Guardian before the release of his new autobiography, Axelrod spoke in frank terms about what he perceives as the corrosive influence of race in the Obama era. The former White House senior adviser said that no other president in US history had had a member of Congress shout at him in the middle of a major address – as Joe Wilson of South Carolina did in 2009 with his notorious “You lie!” rebuke – or face persistent questions about his American citizenship, as Obama did from the so-called “birther” movement.

“The fact is, there are some people who are uncomfortable with the changing demographics of our country,” Axelrod said. “To those people, Obama is a living symbol of something they fear, they don’t like, and some of that has spilled into our politics.”

During the course of back-to-back presidential campaigns as Obama’s top strategist in 2008 and 2012, as well as during two years in the White House before turning to consulting and TV commentary, Axelrod generally kept his thoughts about race to himself. He didn’t want to imply that all political opposition to Obama in Washington was race-based or that the president saw himself as a victim.

“I skirted around the subject. I never talked about it because I never wanted to imply we were ascribing all opposition to race because much of it was just philosophical differences,” Axelrod said.

But more than two years removed from the thick of daily presidential politics, Axelrod clearly feels liberated to speak his mind. “There was no doubt that there was a core of the hostility motivated by race,” he said.

Axelrod’s book, Believer, looks back over his 40 years in politics as a strategist and before that a reporter and columnist for the Chicago Tribune. In one passage that has already proven controversial, he recalls how Obama was “slightly irritated” by the concession call that Mitt Romney, his 2012 Republican opponent, made to the president on election night.

Obama told Axelrod and a small group of other advisers that Romney had congratulated him on getting out the vote “in places like Cleveland and Milwaukee” – a remark that Obama took to refer to black people. “That’s what he thinks this was all about,” Obama said at the time, according to Axelrod.

Over the past week, Axelrod’s account of the conversation has been fiercely disputed by former Romney aides, who have accused Axelrod of lying. Axelrod insisted to the Guardian that “I did not lie. I reported what the president said when he got off the phone.”

The strategist reserves his harshest words in the book for those whom he accuses of whipping up underlying anxieties about race. He writes that “some folks simply refuse to accept the legitimacy of the first black president and are seriously discomforted by the growing diversity of our country. And some craven politicians and rightwing provocateurs have been more than willing to exploit that fear, confusion, and anger.”

Axelrod specifically name-checks the Tea Party movement as having been enhanced by “deep-pocketed Republican oligarchs” for displaying an anger rooted in race. It was, he writes, “a deep-seated resentment of the idea of the black man with the Muslim name in the White House.”

Axelrod says he is sure Obama feels the hostility over race, though “it’s not in his nature or interest to dwell on it”. In a recent interview with Vox, Obama professed to being relatively relaxed about the polarization of US politics along race lines, saying: “I don’t worry about that because I don’t think it’s going to last.”

Axelrod suggested that the race-involved “fear” has reached the higher echelons of the Republican party. Asked whether he thought race in part explained the blockade from the new Republican majority in moving legislation Obama had proposed over the past few weeks, and if so whether the party was motivated by or playing to such prejudices, he replied: “I think a little of both.”

Axelrod added: “There’s been an inflammation of this feeling. There is a sense in the Republican base – and I’m not saying it’s all motivated by race at all – that any cooperation with the president is tantamount to treason.”