A key Republican senator questioned a timeline set by Senate Democrats for wrapping up talks on a bipartisan infrastructure bill, saying it still isn’t clear how the measures would be paid for.

Bill Cassidy, who’s part of a core group of senators negotiating the bill, was responding to Senate Majority Leader Chuck Schumer’s announcement last week that he wants to clear the way for an initial vote next Wednesday on the $579 billion infrastructure package.

“You need a little more time to get it right,” Cassidy said on “Fox News Sunday.” “It can absolutely happen, but you need the pay-fors.”

Cassidy, who was alongside President Joe Biden at the White House in June when the president announced that the deal was moving forward, said Schumer and the White House hasn’t been working with Republicans on the funding question.

Schumer has said he would file for cloture, or to limit debate, on a legislative vehicle for the bipartisan package on Monday that would set up an initial vote Wednesday. That puts pressure on Republicans to cut a deal on a measure that many of them support as a way to channel funding to a range of traditional infrastructure projects.

“I just don’t know how you have a cloture vote when you don’t have the bill written, when you don’t have the pay-fors established,” Cassidy said. “We can get it done, but if they refuse to cooperate on the pay-fors it’s not going to pass. They know that.”