(The Hill) — Sen. Kyrsten Sinema (D-Ariz.) has Democrats and Republicans on the edge of their seats.

With the clock ticking down to the August recess, Senate Majority Leader Charles Schumer (D-N.Y.) desperately wants to pass a bill that would tackle climate change and make significant changes to the tax code. But Schumer doesn’t have the votes — at least not yet.

Schumer says he’s working on Sinema and hopes she’ll be a “yes” on the motion to proceed to the measure, but the Arizona centrist hasn’t said whether she backs it. 

“We’re in touch with Sen. Sinema, we’re in touch with all of the members, and we’re hopeful — I’m very hopeful — we’re all going to stay united and pass this bill,” he said Tuesday afternoon.  

Schumer unveiled the tax and climate deal he struck with Sen. Joe Manchin (D-W.Va.) on July 27 after more than a week of secret negotiations. The bill would implement a 15 percent minimum tax on wealthy corporations and enact new energy and climate programs.

Seven days later, Senate Democrats still don’t know where Sinema stands. Her office says she is reviewing the legislation and waiting for the Senate parliamentarian’s review of the text. 

That means senators may not know how Sinema will vote until they bring the more than 700-page bill to the floor on Thursday or Friday.  

A Democratic senator who attended a virtual meeting of the caucus Tuesday said Sinema didn’t speak up about the bill at the meeting.

Republicans think there’s a good chance that Sinema may derail the legislation.

Senate Minority Leader Mitch McConnell (R-Ky.) slammed the deal as “terrible.”

“I would say to our friend Joe Manchin, he made a terrible deal, a terrible deal. How he can defend this from a West Virginia point of view or think of it as a centrist kind of agreement is astonishing,” he said. 

Sen. Kevin Cramer (R-N.D.) believes Sinema will stick to her moderate principles. 

“I always have faith in her. I don’t know how it will come out,” he said. “I have great faith she’s going to do what she feels is right. She’s more convicted than she is transactional.” 

He predicted the climate and tax provisions in the bill will become a major issue in the midterm elections if they are seen as fueling inflation or dampening corporate investment. 

Sinema, who has repeatedly angered progressives in this Congress, will likely face a primary challenge no matter how she votes on the Schumer-Manchin bill.

As the uncertainty builds, Manchin is waging a charm offensive to win over Sinema after he left her out of the secret negotiations with Schumer. 

Manchin and Sinema worked together on last year’s bipartisan infrastructure bill and have stood together to oppose efforts by liberal colleagues to change the Senate’s filibuster rule. 

But now their relationship is being tested after Manchin cut a deal with Schumer to reform the tax code and spend $369 billion on new energy security and climate change programs. News of the agreement caught Sinema and just about everyone else in Washington by surprise.  

Manchin left Sinema a message on Monday in hopes of talking to her and explaining why he struck the deal and why she should support it. He tried to catch her on the floor for a conversation during the Monday evening vote, but without success. 

Manchin finally tracked down his colleague on Tuesday when she was scheduled to preside over the floor, a duty routinely assigned to more junior members of the upper chamber. 

Television cameras caught Manchin kneeling on the chamber’s blue carpet next to the presiding officer’s desk, seemingly trying to cajole Sinema.

Democrats still don’t know whether Sinema will vote for the bill after Manchin insisted on adding a provision to close the carried interest tax loophole. 

The carried interest tax loophole allows asset managers to use a favorable tax rate on income. A proposal to close it was left out of last year’s House tax reform package after Sinema opposed it. 

Asked if she had spoken to Sinema or felt concerned that the Arizona senator might “tank” the deal, Sen. Elizabeth Warren (D-Mass.) said: “I’m not talking about private conversations. It will take 50 votes to get it through.”

All Republicans are expected to reject the bill, meaning Democrats cannot afford one defection.

Manchin provided little detail when asked how his talk with Sinema went. 

“We had a nice time. We had a nice time. Next?” Manchin said tersely, looking to change the subject when pressed by reporters Tuesday afternoon. 

Recognizing that Sinema could scuttle his deal with Schumer if she votes “no,” Manchin told reporters Tuesday that he’s doing his best to explain to her why he cut the deal and why it makes good sense for the country. 

He also signaled that he’s open to considering any changes she might propose.  

“We’re exchanging texts back and forth,” he said. She’s “extremely bright, she works hard, she makes good decisions based on facts. I’m reliant on that.”

Manchin said he and Schumer are “working with all the caucus” to get buy-in from all 50 members of the Democratic caucus. 

“We’re just basically exchanging back and forth, whatever I have that she hasn’t seen. And our staffs are working together very closely,” he said, adding he’s also exchanging materials relevant to the bill with other Democratic and Republican senators. 

Asked if he would be willing to change the bill’s carried interest provision, Manchin responded: “Everyone is still talking.” 

Manchin on Tuesday defended his push to close the loophole that allows money managers to pay capital gains tax rates on income they collect from advising on profitable investments. 

He told reporters last week that he was “adamant” about including it in the budget reconciliation package. 

Asked whether Sinema is upset that she didn’t get looped in to last week’s secret talks, Manchin said he didn’t loop anyone else in to the private discussions with Schumer because he didn’t want to disappoint any of his colleagues by getting their hopes up just in case the talks fell apart again. 

“She’s my dear friend,” he said. “But why bring anyone in and all their aspirations get high and the drama we go through and it doesn’t work out?

“I wasn’t really sure” a deal could be reached, he said. “I’m not in control of the timing” of the announcement of the deal, “Sen. Schumer is in control of the timing.”

But Manchin rejected the notion that Sinema or any other senator has reason to be upset because he negotiated the climate and tax deal with Schumer in secret. 

“People getting mad because they think this is some kind of orchestrated coup against them is just so wrong,” he added.