Washington (AFP) - President Joe Biden sought again to woo working white Americans, fine-tuning his words as he wages an all but official campaign for re-election and hoping to win over a demographic that snubbed him in 2020. 

"No billionaire should be paying a lower tax rate than a firefighter," Biden said in a speech to firefighters on Monday.

Since the start of his term in the White House, Biden, now 80, has told the same stories about growing up in a blue collar, middle class family in the factory town of Scranton, Pennsylvania.

But since his State of the Union address to Congress on February 7 -- seen as the informal start of his quest for another term -- Biden has really hammered away at this image of himself as a man of the people, a regular guy who can sympathize with families struggling to make ends meet.

In his speeches these days -- like Monday before the first union to endorse him in 2020, the International Association of Fire Fighters -- the flow of his message has been practically predictable.

First comes an obligatory reference to his father, who Biden depicts as an example of proud, hardworking folk and would often say to him, "Joey, a job is about a lot more than a paycheck. It's about your dignity."

"It's about being able to look your kid in the eye and say, 'Honey, it's going to be OK,' and mean it," Biden said in his February 7 address. He has repeated these words often since then.

Then there is Biden's frequent allusion to his no-frills childhood home -- three rooms for his parents, four children and a grandfather -- which he bills as certifying his middle class credentials. 

Biden also likes to talk about the need for everybody to pay their fair share of taxes, but does so with a nod to the glory of free enterprise in the country where it is sacrosanct.

"I'm a capitalist. You want to go and make a lot of money? Go and do it but at least pay something," Biden told the firefighters on Monday.

"Do you know what their average tax rate is? t-h-r-e-e %. Poor people," Biden said, joking about billionaires. Biden will unveil the annual federal budget blueprint on Thursday and has again pledged to raise taxes on the rich.

When he talks like this Biden, who has said he "intends" to seek a second term in office but has not officially launched a campaign, is fine-tuning his words to appeal to a very specific demographic: working class white people without a college degree.

In 2020, Biden won the election in large part due to support from Black people and university graduates. Now, he knows he has his work cut out. A recent Washington Post/ABC poll found that only 31 percent of voters without a college diploma are satisfied with his economic policy, while among people who do have a degree the proportion is 50 percent.

Then there is Trump

In 2016 and again in 2020, around two-thirds of white voters without a college degree opted for Donald Trump, who has already launched a campaign for the 2024 election.

So Biden addresses very specific issues as he tries to lure those people wary of him.

To Americans who struggle to grasp his big plans to overhaul decrepit US infrastructure, boost people's purchasing power or transition away from fossil fuels, Biden speaks at length in language that is easier to understand: he says US roads are in horrible shape, bank overdraft fees are outrageous and insulin for diabetics costs too much.

Keenly aware that for the past 20 years older white Americans tend to vote Republican, Biden also talks a lot about the national retirement benefit system, or Social Security, the health care program for seniors, or Medicare, and his government's efforts to fight cancer.

Biden regularly accuses Republicans of wanting to gut these programs, seeking to embarrass a party that is historically averse to big-government intervention in the economy, like spending on such programs. But the party is also torn -- it knows that preserving Medicare and Social Security is dear to many of its voters.

Trump got the message. In a speech Saturday to CPAC, a big annual conference of conservative leaders and followers, he pounced on economic and social issues, insisting America is going down the tubes and only he can save it.

But Trump now bills himself as a defender of Social Security and Medicare spending, a position which allows him to take jabs at other possible Republican presidential hopefuls who favor leaner government spending.