Barack Obama, Nancy Pelosi and dozens of members of Congress will converge on Glasgow this week, as COP26 enters its final few days, without any prospect of the US passing key climate-focused legislation before it ends.

The senior US politicians will fly to Scotland following a frantic few days on Capitol Hill, where US President Joe Biden managed to get his signature infrastructure bill through Congress, though without any of the major climate initiatives he had promised.

Many of those have instead been placed into a second piece of legislation, the fate of which remains uncertain as moderate Democrats continue to hold out for more information on how it will be paid for.

With days left until the end of the summit, climate activists have expressed disappointment about the lack of firm US commitments. But they are hoping the presence of so many members of Congress in Glasgow will give them a chance to press the case for passing Biden’s $1.75tn social security package, which includes around $550bn of environmental provisions.

Ramon Cruz, the president of the Sierra Club, an environmental organisation, told the Financial Times: “What happened this week in Congress is not ideal . . .

The infrastructure package is not enough, it is not sufficient. ”

“But we know that this is not the end of the road and we have to pass the legislation that could transform lives. Build Back Better [the social security bill] is such transformational legislation.”

Biden has promised to put tackling climate change at the heart of his domestic agenda and attended the Glasgow summit in person last week. But his administration disappointed many attendees when it refused to sign up to a nation agreement.

The White House on Sunday insisted it remained committed to the climate agenda, pointing out the range of measures in the Build Back Better bill.