WASHINGTON — Hardline conservative Republicans in the US Senate and billionaire Elon Musk showed no sign of softening opposition to President Donald Trump’s tax-cut and spending bill on Wednesday, as they pushed for deeper reductions in government outlays.

The nonpartisan Congressional Budget Office on Wednesday estimated the bill — which would extend Trump’s 2017 tax cuts and step up spending for the military and border security — will add about US$2.4 trillion (RM10.2 trillion) to the US$36.2 trillion US debt pile.

Another nonpartisan forecaster, the Committee for a Responsible Federal Budget said on Wednesday that when taking interest payments into account the bill’s cost could rise to US$3 trillion over a decade or to US$5 trillion if temporary tax cuts were made permanent.

Musk, the world’s richest person who for several months led the Department of Government Efficiency cost-cutting effort, stepped up his attacks on the measure, joining with Senate Republican deficit hawks who said the version passed by the House of Representatives last month did not sufficiently cut spending.

“A new spending bill should be drafted that doesn’t massively grow the deficit,” Musk, the largest Republican donor in the 2024 election cycle, said on his X social media platform. “America is in the fast lane to debt slavery.”