U.S. Bernie Sanders, I-Vt., delivered a highly critical speech on the Senate floor Tuesday about the deal Sen. Joe Manchin, D-W.Va., struck last week with Democratic leadership to advance portions of the party’s agenda. 

The legislation, called the Inflation Reduction Act, would make the country’s greatest investment yet in fighting climate change, extend health insurance subsidies and lower the price of prescription drugs. But the measure pales in comparison to President Joe Biden’s Build Back Better legislation, which Sanders had championed and Manchin had torpedoed.

The compromise, negotiated by Senate Majority Leader Chuck Schumer, D-N.Y., “has some good features, but also some very bad features,” Sanders told colleagues Tuesday in his first public remarks about the bill.

Sanders’ vote will be critical to advancing the legislation in the evenly divided Senate — and he did not threaten to oppose it. But he did call on the Senate to thoroughly vet and amend the bill, which leadership hopes to fast-track this week.

Sanders’ office did not immediately respond Wednesday morning to an inquiry about how he would vote if the legislation were not amended. A spokesperson for Vermont’s other U.S. senator, Democrat Patrick Leahy, said he did not know how his boss would vote on the bill.

In his floor speech, Sanders said the bill should be beefed up before it passes, to include elements of Build Back Better that did not make it into the Manchin deal — including measures to address homelessness, student debt, child care and Medicare.

Sanders addressed his remarks directly to Americans who face those issues: “This bill turns its back on you.”

While the bill would provide more funding to combat climate change than ever before, Sanders said it would still provide substantially less money than Build Back Better. Sanders criticized tax breaks for the fossil fuel industry that the bill contains, on top of existing tax breaks the fossil fuel industry receives every year.

“If we are going to make our planet healthy and habitable for future generations, we cannot provide billions of dollars in new tax breaks to fossil fuel companies that are destroying the planet,” Sanders said.

On the plus side, Sanders said, the bill would require corporations to pay a minimum tax of 15% and it would provide funding to the IRS to audit “wealthy tax cheats,” as he put it. 

However, Sanders complained that the bill would not repeal Trump-era tax breaks for large corporations and the wealthiest Americans. Sanders said the top 1% of Americans are receiving 83% of the benefits of Trump-era tax breaks. 

Sanders’ frustration with the bill was evident throughout his speech and he urged his fellow senators to step up: “Now is the time for every member of the Senate to study this bill thoroughly and to come up with amendments and suggestions as to how we can improve it.”