With eight small words in a television program, Manchin, Joe Biden's party comrade, seems to have killed the comprehensive reform package that would crown Biden's first, and perhaps only, presidency.
Build back better, or BBB, was one of Joe Biden's most important election promises and a recurring slogan.
If the Biden administration does not succeed in turning Manchin around, this will be Joe Biden's most difficult domestic political defeat to date.
Admittedly, parts of what was included in the election slogan have already been implemented.
The roll-out of vaccines and financial support for people and companies were voted through in March, and a major investment in infrastructure became, albeit diluted, a law a month ago.
"Most important part of Biden's election promise"
What remained was perhaps the most important part of Biden's election promise, the one that was given the same name as the president's slogan.
Build back Better can simply be described as a third welfare package with, for example, child allowance of SEK 3,000 a month and free preschool for 3- and 4-year-olds.
One third of climate-related initiatives for a green transition (about $ 500 billion) that would significantly reduce US emissions.
Among other things, the US Postal Service will change its 165,000 petrol and diesel cars to electric cars.
And then a third with money for, for example, investments in housing and price caps on certain drugs.
Now the future of those proposals is uncertain.
Manchin has explained his message by saying that he does not want to increase the already astronomical US government debt, but also by saying that he is worried about inflation and the rising prices of electricity, petrol and other things.
The US inflation rate was 6.8 percent in November, the highest figure in 40 years.
More things come into play
But there is also reason to assume that more things come into play in Manchin's decision.
Manchin is something as unusual as a Democratic senator from a very Republican state.
In West Virginia, there was a difference of almost 40 percentage points between Joe Biden (29.7%) and Donald Trump (68.6%).
Nevertheless, Manchin barely managed to stay in the Senate in the last Interim Election 2018.
But that means the senator knows that his home base of voters is largely made up of people willing to vote for a Republican.
West Virginia, also known as the coal state, is heavily dependent on the fossil fuel industry, and Biden's promises of a green transition are therefore causing great concern among Manchin's voters.
Now it remains for the White House to try to save what can be saved in the BBB.
In this context, it must hurt Joe Biden that he went to the polls as a center-right democrat - and now his perhaps most important election promise was overturned by another center-right democrat.