(NewsNation) — In a rare Saturday session, Senate Democrats are pushing closer to passing what will be a cornerstone of President Joe Biden’s agenda.

The Inflation Reduction Act, one of the Senate’s big-budget bills for the year, is a wide-ranging package addressing climate change, energy, health care costs, taxes and even deficit reduction.

It also is moving through the Senate under special rules, the most important being it only takes 51 votes instead of 60 to pass.

This is crucial because it means Democrats can pass it without any Republican votes — which is expected to happen.

Another rule is that once this debate is over, both sides get to propose an unlimited number of amendments.

Usually, if one party isn’t happy about the bill — in this case, Republicans — they may propose hundreds.

They come one after the other and voting on these amendments takes hours, sometimes multiple days.

The marathon session is called a “vote-a rama” of amendments.

So what’s actually in the bill?

The highlights of the Inflation Reduction Act are some long-time Democratic priorities.

• Sets aside $300 billion for climate change infrastructure
• Allows the federal government to negotiate lower costs of drugs for Medicare recipients
• Sets a 15% mandatory minimum tax rate for corporations
• Provides $80 billion to the Internal Revenue Service to beef up the agency after years of cuts

Democrats say the bill will bring in more revenue than it costs and will reduce the federal deficit over a six-year period.

“This is one of the most comprehensive and far-reaching pieces of legislation that has come before Congress in decades,” Senate Majority Leader Chuck Schumer said.

And some economists agree, though others say the bill could add to inflation in the short term.

Republicans call it the wrong policy at the wrong time.

Senate Minority Leader Mitch McConnell, R-Ky., says despite Democrats’ promises, it could end up raising middle-class taxes.

“Democrats have already robbed American families once through inflation and now their solution is to rob American families yet a second time,” McConnell said.

On Saturday, a major Dem priority was cut out of the bill.

One thing this bill did was penalize drug companies for spiking their prices up higher than the rate of inflation.

Because this is one of those unique budget bills, everything in it has to be related to spending or taxes.

Elizabeth MacDonough, the Senate parliamentarian, who serves as a sort of Senate rules referee, gets to decide what’s related and what has to be cut.

The drug company measure, MacDonough ruled, was not related to the budget or taxes, so she took it out.

As the chamber’s nonpartisan rules arbiter, MacDonough said lawmakers must remove language imposing hefty penalties on drugmakers that boost their prices beyond inflation in the private insurance market.