The top four leaders of Congress will meet with Treasury Secretary Steven Mnuchin at 11 a.m. on Sunday, hours before a crucial procedural vote to advance the massive stimulus bill, according to three sources with knowledge of the plans.

The meeting is in Senate Majority Leader Mitch McConnell’s office, and also will include House Minority Leader Kevin McCarthy, Senate Minority Leader Chuck Schumer and House Speaker Nancy Pelosi.

While negotiators are close to a deal on the Senate side, it’s still uncertain whether Pelosi will get behind it or will seek to make changes to the measure when it gets to the House.

What’s in the stimulus package?

It’s not clear yet, but it looks like it will be big. People directly involved in the negotiations tell CNN it could top a cost of $1.5 trillion.

Larry Kudlow, a top economic adviser to Trump, went even further in estimating the overall scope of the package Saturday, telling reporters it could top $2 trillion.

«The package is coming in about 10% of GDP, it’s a very large package,» Kudlow, the director of the National Economic Council, said. Ten percent of gross domestic product is roughly $2 trillion.

Read more about the package here.