As US president Joe Biden and Democrats in Congress ploughed ahead with their plan to pass a $1.9tn fiscal stimulus bill this week, they faced a sudden, unwelcome roadblock from within their own political sphere.

Lawrence Summers, who served as Bill Clinton’s treasury secretary and Barack Obama’s top economic adviser, warned that Biden’s plan was excessive and that it might trigger “inflationary pressures of a kind we have not seen in a generation, with consequences for the value of the dollar and financial stability”.

Summers’ scepticism, delivered in a Washington Post op-ed on Thursday, clashed with the nearly universal backing among left-leaning economists for Biden’s argument that the US needed to “go big” with massive government support to tackle the still-raging pandemic.

The message from Summers struck a nerve. By Friday morning, a fierce backlash to his comments was building both inside the White House, among Democrats on Capitol Hill, as well as progressive activists — reflecting fears that the intervention could open up an internal rift within the party at a critical stage.

Part of the anger directed at Summers reflects the Biden White House’s desire to avoid repeating the mistakes of the 2008-09 financial crisis, when the US fiscal response was limited, in part because President Barack Obama sought Republican support for his policies. Summers led Obama’s National Economic Council at the time.

“Worrying about ‘overheating’ when the job market recovery has stalled out is foolish in the extreme,” one Biden administration official told the Financial Times. “Of course there are risks associated with going big, but as we’ve said all along, those risks pale compared to the risks of going small. As Summers himself should remember.”

Speaking to the FT on Friday afternoon, Summers defended his stance. “I'm all for fiscal stimulus. I am very much a believer that the dangers of doing too little are greater than the dangers of doing too much,” he said.

“That's not an argument to justify any level of fiscal stimulus and, for the reasons I articulate in my piece, a $1.9tn programme on top of the $900bn programme passed in December raises concerns about inflationary pressures and about limiting space for profoundly important public investments”, he added.

In a briefing with reporters on Friday, Jared Bernstein, a member of Biden’s White House council of economic advisers, said the administration believed it was crucial to “hit back hard” and “hit back strong” with fiscal support and said there was “complete consensus” within the team on the calibration and size of the package.

He also said Summers was “flat out wrong” in suggesting the administration was underplaying inflation dangers. “Janet Yellen is our treasury secretary, OK? ,” he said referring to the former Fed chair. “She knows a little something about inflationary risks and has tracked that economic issue forever.”

But Summers responded: “I'm not aware of any historical instances in which there was a gradual increase in rates that brought inflation under control without causing a recession. Given the kind of forward guidance given by the Fed and the magnitude of the debt, engineering a soft landing is going to be more difficult than in the past.”

Summers’ position received the backing of Olivier Blanchard, the former chief economist of the IMF, as the debate over his comments intensified. “I am known as a dove. I believe that the absolute priority is to protect people and firms affected by Covid. Still, I agree with Summers,” Blanchard wrote on Twitter. “The 1.9tn program could overheat the economy so badly as to be counterproductive. Protection can be achieved with less.”

Speaking to reporters on Friday morning, Kristalina Georgieva, the managing director of the IMF, said the US needed to be “watchful” of the dangers Summers raised but added that the US had the “best possible” treasury secretary in Yellen to monitor challenges to financial stability.

She was also broadly supportive of Biden’s plan. “We believe that using this fiscal space, given the exceptional uncertainties, and most importantly, given the fact that there is still a lot of pain for households and businesses in the US, is appropriate,” Georgieva added.

The Biden administration has argued that it is necessary to administer such a large relief package now in order to help the US economy weather the recent slowdown in the labour market and sustain the recovery broadly through September, when vaccinations will be more broadly widespread.

In addition, US officials want to prevent long-term scarring from the pandemic, which has hit low-wage workers and minorities the hardest.

Summers’ argument was not just about the economic risks of the large stimulus bill, but also about the political danger. He worries that it could use up too much of the new administration and Congress’s bandwidth, possibly limiting Biden’s other goals.

The White House has rejected a Republican offer for a smaller stimulus proposal, worth $600bn, judging it to be insufficient, so the chances of broad bipartisan support in Congress have dwindled dramatically.

“If the stimulus proposal is enacted, Congress will have committed 15 per cent of GDP with essentially no increase in public investment to address these challenges. After resolving the coronavirus crisis, how will political and economic space be found for the public investments that should be the nation’s highest priority?,” Summers wrote in the op-ed.

But the criticism of Summers from many Democrats on Friday was withering. “Why would we listen to the economist who admits he went too small last time if he’s warning us to go small again? I swear this town is nuts. It’s like people can only remember thirty names and so they just keep going back to the same people,” said Brian Schatz, the Democratic senator from Hawaii.