5 former Treasury secretaries — including one of George W. Bush's — throw their support behind Manchin's inflation-fighting bill

• Five former Treasury secretaries backed Manchin's inflation-fighting bill in a Wednesday statement.
• The group includes secretaries from the George W. Bush, Clinton, and Obama administrations.

Sen. Joe Manchin just won valuable new backing for his plan to fight inflation.

A group of five former treasury secretaries threw their support behind the Inflation Reduction Act in a Wednesday statement. The proposal, brokered by Manchin and Senate Majority Chuck Schumer last week, offers a path forward for some of President Joe Biden's economic agenda. The signatories include secretaries from Democratic and Republican administrations alike, lending the plan bipartisan approval that it's unlikely to win in Congress.

The former treasury secretaries backing the proposal are:

• Larry Summers, who served under President Bill Clinton
• Robert Rubin, who served under President Bill Clinton
• Hank Paulson, who served under President George W. Bush
• Tim Geithner, who served under President Barack Obama
• Jacob Lew, who served under President Barack Obama

"This legislation will help increase American competitiveness, address our climate crisis, lower costs for families, and fight inflation — and should be passed immediately by Congress," the group said.

The statement comes as Democrats scramble to gather the necessary support to pass the bill in the Senate. Sen. Kyrsten Sinema of Arizona is the biggest unknown within the party's ranks, and her stance can either secure the bill's passage or tank it entirely. Sinema hasn't weighed in on the measure yet, and the plan's proposal to close the carried-interest loophole could sway her against the bill. The Arizona senator has opposed closing the loophole in the past.

That's prompted a mad dash among Democrats and Republicans to win Sinema over. Republicans have pointed to estimates from the Joint Committee on Taxation that suggests the proposed 15% minimum corporate tax on large, profitable companies will trickle down to most Americans. Democrats, meanwhile, argue the projections don't tell the entire story, and other aspects of the IRA would provide most Americans with a net financial benefit.

Other estimates tout the proposal as a boon for the US economy. The plan, if approved, "will nudge the economy and inflation in the right direction," Moody's Analytics said in a Monday note. The firm's analysts forecast the plan will modestly cool price growth and boost economic output over the next decade. Not approving the IRA, however, could worsen the inflation problem by allowing ACA credits to expire and saddling millions of Americans with higher health care costs.

If the treasury secretaries' statement is to change any senators' minds, it has little time to do so. The Senate is likely to vote on the plan later this week, and Manchin has said he'll personally pitch the IRA to Sinema in hopes of winning her over and sending the plan to Biden's desk. But with the Senate barreling toward an August recess, the Arizona senator will have considerably less time to consider the plan than Manchin did.