House Republican leadership is coming to grips with needing to revise its debt ceiling bill to get through its own caucus, senior GOP sources tell Axios.

Why it matters: This is Kevin McCarthy’s first real legislative challenge as speaker. Failure to get a deal that raises the government’s debt ceiling means catastrophic default on the national debt.

• Republicans feel emboldened by the growing number of Democrats calling on President Biden to negotiate if the House passes a debt ceiling proposal.
• Getting that done with a deadline coming as soon as June is hard.

Behind the scenes: “It’ll have to be tweaked, no chance for this bill to stay the same,” a senior GOP source told Axios.

• “As far as we’re concerned, this is already a done deal,” another GOP lawmaker said. “But you know, never say never.”

Zoom in: House leadership knows it’s risky to agree to change anything in the package, which could lead to a series of fresh demands.

• Many House Republicans see themselves as free agents — and not terribly afraid of the speaker — sensing his thin majority leaves him without much leverage.
• But a few sticking points — such as the plan opposed by Midwestern Republicans to cut ethanol and biodiesel tax credits — might be tough enough to force revisions, according to leadership sources.
• Top Republicans are reassuring concerned members that the goal is to get to the negotiating table with Biden, and to not stress the specifics just yet.

Between the lines: Leadership sources expect the bill’s call for a one-year extension to get extended beyond the 2024 elections during negotiations.

• Biden’s “not gonna want to take a vote … right before his reelection,” a senior House Republican told Axios.

The bottom line: Biden has already started to attack Republicans based on the proposal.

• “They’d rather threaten a default on the U.S. economy … than get rid of $30 billion in taxpayer subsidies to an oil industry that made $200 billion last year,” he said on Friday — referencing the proposed cuts to green energy tax credits.