Republicans leaders in the House of Representatives announced Wednesday night that they will vote on Thursday to replace Obamacare with a renegotiated Trumpcare bill they expect will pass.

After months of haggling, Republicans expressed confidence they had finally crafted a bill that will get the 216 votes necessary. “Do we have the votes? Yes. Will we pass it? Yes,” said Majority Leader Kevin McCarthy, the second-highest ranking Republican.

The Trump administration is putting enormous pressure on members to support the new president in his first major legislative initiative, and it’s possible that McCarthy and Republican leaders are calling the vote and projecting confidence as a final lean on squishy members.

If more than 22 Republicans vote against the bill and no Democrats vote for it, as expected, then the bill will fail. At least three dozen members are either opposed or have not taken a public position, according to a count by HuffPost. The margin for error is so narrow that Republican Rep. Jason Chaffetz of Utah is flying back early from Utah after he abruptly left last week to have foot surgery.

“We must not let them succeed,” House Minority Leader Nancy Pelosi said of Republicans in a speech at Emily’s List annual gala Wednesday night.

The real-world consequences of the bill are mostly unknown since House Republicans are voting before the Congressional Budget Office (CBO) has had an opportunity to analyze the legislative text. They have yet to have any hearings on the new bill and were still changing the official legislative text when they announced the vote late Wednesday.

When Republicans attempted to pass the first version of Trumpcare in March, the CBO estimated that 24 million fewer people would have health insurance in the next decade if it became law. This amended version would allow states to obtain a waiver to opt out of health insurance regulations, including the requirement that companies do not discriminate against people with pre-existing conditions. Insurance companies could then charge people with preexisting conditions several times more for coverage. States would also set up high-risk pools to help those patients but the proposals floated so far have not had sufficient funds to avoid passing on the enormous premium hikes.

The new bill will also allow insurance companies to charge the elderly up to five times more for health insurance than the young and decrease insurance subsidies for the elderly. The powerful AARP has deemed the new bill an “age tax.”

The changes were made in response to demands of the conservative House Freedom Caucus and other conservative outside groups who had largely opposed the last attempt to repeal Obamacare. They argued that more health insurance regulations had to be repealed in order to bring down premiums, regulations which Democrats argue protect consumers and ensure that all people receive adequate health coverage.

Unlike the last attempt at repealing Obamacare that ended in criticism from both sides of the aisle, conservative outside groups and members of Congress have been throwing their support behind the bill or simply remaining neutral. The House Freedom Caucus, the most prominent opponents of the last bill, officially endorsed the new bill, along with the influential group Club for Growth. Heritage Action, which opposed the bill in March, said they would not take a position on the current bill.